Apparatus and method for stripping solder metals during the recycling of waste electrical and electronic equipment

ABSTRACT

Apparatuses and processes for recycling printed wire boards, wherein electronic components, precious metals and base metals may be collected for reuse and recycling. The apparatuses generally include a mechanical solder removal module and/or a thermal module, a chemical solder removal module, and a precious metal leaching module, wherein the modules are attached for continuous passage of the e-waste from module to module.

FIELD

The present invention relates generally to apparatuses and processes forrecycling waste electrical and electronic equipment such as printed wireboards to separate materials including, but not limited to, preciousmetals, base metals, solder metals, and working integrated circuits.

DESCRIPTION OF THE RELATED ART

Disposal of used electronic equipment including obsolete or damagedcomputers, computer monitors, television receivers, cellular telephones,and similar products, is increasing at a rapid rate. It is recognizedthat there are significant hazards to living things and to theenvironment generally when electronic equipment is dumped in landfills.Equally, it is understood that improper disassembly poses appreciablerisks to the health and safety of people performing disassemblymanually.

Printed wire boards (PWBs) are a common element of many electronicsystems. PWBs are typically manufactured by laminating dry film on cleancopper foil, which is supported on a fiberglass plate matrix. The filmis exposed with a film negative of the circuit board design, and anetcher is used to remove unmasked copper foil from the plate. Solder isthen applied over the unetched copper on the board. Depending upon theuse and design of the particular PWB, various other metals may be usedin the manufacturing process, including lead, tin, nickel, iron, zinc,aluminum, silver, gold, platinum, palladium, and mercury. The PWBsinclude many additional components, for example, transistors,capacitors, heat sinks, integrated circuits (IC's), resistors,integrated switches, processors, etc.

PWBs are potentially a difficult waste material to process since theygenerally have little usefulness once they are removed from theelectrical system in which they were installed. In addition, theytypically consist of materials that classify them as a hazardous or“special” waste stream. They must be segregated and handled separatelyfrom other nonhazardous solid waste streams. PWBs that are handled aswaste materials must be processed using any one of several availabledisposal options. Not only are these options expensive, they require asignificant amount of effort and handling by the generator. Furthermore,since some of these disposal options do not include destruction of thewaste circuit boards, the generator also retains much of the liabilityassociated with improper handling or disposal.

Different methods have been suggested to try to combat the waste of rawmaterials and environmental pollution caused by the ever increasing loadof scrap electronic waste. To date, methods requiring a high energydemand are needed to separate the materials so that they can berecycled. Mechanical and hydrometallurgical methods have been thetraditional methods of recycling of waste PWBs, which comprise grindingof the whole waste, followed by attempts to separate and concentratedifferent material streams. Disadvantageously, when PWBs are ground,only the plastic fraction can be effectively liberated from metals andtoxic gases are evolved. Accordingly, mechanical methods do not resultin high recovery rates, especially for precious metals. Inhydrometallurgical methods, large amounts of chemicals are used,generating huge quantities of waste acids and sludge, which have to bedisposed as hazardous waste. Furthermore, the overall processes ofrecycling of various metals by chemical processes are very long andcomplicated. Thermal methods, including pyrometallurgical processing ofwaste PWBs, result in the emission of hazardous chemicals to theatmosphere and water as the result of thermal degradation of epoxy(formation of dioxins and furans) and volatilization of metals(including Pb, Sb, As and Ga). Thermal methods are further characterizedby high energy consumption, and the necessity to use expensive exhaustgas purification systems and corrosion resistance equipment.

Further, disadvantageously, the present methods of extracting preciousmetals (e.g., gold) from materials include using toxic and/or expensivechemicals (i.e., lixiviants) to leach the gold from the material. One ofthe oldest commercial processes for dissolving gold is the so-called“cyanide process” whereby the cyanide ion forms such a stable complexwith gold. The effectiveness of the cyanide process has led to itscommercial usage for both extraction of gold from its ores and for thereclamation of gold from gold coated scrap parts. Generally, a potassiumcyanide solution is used in the “cyanide process.” Disadvantageously,this solution is very toxic and disposing of spent cyanide solution hasbecome a significant and increasing waste disposal and pollutionabatement control problem. Gold has also been dissolved using a mixtureof hydrochloric acid and nitric acid, known as “aqua regia,” in order toobtain the complex chlorauric acid, HAuCl₄. Aqua regia, however, isextremely corrosive, yields toxic fumes, and does not have anyselectivity for precious metals.

Printed wire boards without any components and solder (i.e., bareboards) represent a material that is much easier to recycle thanpopulated circuit boards with mounted components, since bare boards bythemselves consist only of copper and fiberglass foils glued by epoxywith some gold/nickel/copper plating on their surface. As bare boardrepresents 65-70% by weight of an average populated printed circuitboard, removal of components from the board leads to formation of aneasily-recyclable material fraction, which represents 65-70% of thetotal volume. This approach is more advantageous compared to commonpractice of size reduction applied to the whole incoming materialvolume. Moreover, once removed from the boards, recovered components maybe sorted and sold by type, such as components containing tantalum orcomponents that can be reused, thereby generating multiple productstreams with a higher retail value than just a mix of components.

Thus, a need exists for a method of recycling waste electrical andelectronic equipment such as printed wire board components thatovercomes or minimizes the above-referenced problems.

SUMMARY

The present invention relates generally to apparatuses and processes forrecycling printed wire boards to separate materials for reuse and/orrecovery. More particularly, the present invention relates generally toapparatuses and processes for recycling PWBs to efficiently recoverprecious metals, base metals, solder metals, and working integratedcircuits while minimizing the amount of commodity chemicals and otherresources used.

In one aspect, an apparatus for processing e-waste is described, saidapparatus comprising:

(a) a mechanical solder removal module; and(b) a chemical solder removal module;wherein the modules are contiguously attached to one another.

In another aspect, a method of recycling e-waste is described, saidmethod comprising:

removing at least a portion of the solder using a mechanical solderremover, wherein the mechanical solder remover comprises at least oneblade and at least one agitator for the mechanical removal of solderfrom the surface;removing at least a portion of the solder using a chemical solderremover, wherein the chemical solder remover comprises a container for afirst composition and at least one agitator, wherein the PWB ispartially immersed in the first composition; andremoving at least a portion of a precious metal using a leachingcomposition.

In still another aspect, an apparatus for processing e-waste isdescribed, said apparatus comprising:

(a) a heating module for removing casing or epoxied components from aPWB; and(b) a chemical solder removal module,wherein the modules are contiguously attached to one another.

In yet another aspect, a method of recycling e-waste is described, saidmethod comprising:

removing at least one casing from a PWB using a heating module, whereinthe heating module comprises a heating mechanism and a means for movingthe PWB through the heating mechanism;removing at least a portion of the solder using a chemical solderremover, wherein the chemical solder remover comprises a container for afirst composition and at least one agitator, wherein the PWB ispartially immersed in the first composition; andremoving at least a portion of a precious metal using a leachingcomposition.

Other aspects, features and advantages will be more fully apparent fromthe ensuing disclosure and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the generalized apparatus and process for recyclingprinted wire boards.

FIG. 2 illustrates the partial immersion of the recycling printed wireboards in the chemical solder remover composition.

FIG. 3 illustrates an embodiment of the apparatus for solder removalfrom a printed wire board.

FIG. 4 illustrates another embodiment of the apparatus for solderremoval from a printed wire board.

FIG. 5 illustrates an embodiment of the apparatus for gold leaching fromprinted wire boards and/or printed wire board components.

FIG. 6 illustrates the generalized apparatus for recycling printed wireboards.

FIG. 7 is a top view in the internal components of a thermal desolderingunit.

FIG. 8 is a front view of the internal components of the thermaldesoldering unit of FIG. 7.

FIG. 9 is a side view of the internal components of the thermaldesoldering unit of FIG. 7.

FIG. 10 is a cell phone PWB before heating (A) and after heating (B)

FIG. 11 is the cell phone PWB of FIG. 10(A) before chemical desoldering(A) and after chemical desoldering.

DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS THEREOF

The present invention relates generally to apparatuses and processes forrecycling printed wire boards, integrated circuits and printed wireboard components to separate materials for reuse and/or recovery. Moreparticularly, the present invention relates generally to apparatuses andprocesses for recycling PWBs to more efficiently recover and separatemetals and working components, while simultaneously minimizing the useof commodity chemicals and other resources.

As introduced in the background section, the traditional methods ofrecycling of waste PWBs result in environmental contamination, high costexpenditure and low efficiency. In contrast, the apparatuses and methodsdescribed herein are based on a differential approach to the recyclingof materials, wherein the various parts of the waste PWBs are separatedbased on appearance and physical and chemical properties.

Processes for removing at least one recyclable material from a printedwire board (PWB) were previously described in International PatentApplication No. PCT/US2011/032675 filed on Apr. 15, 2011 in the name ofAndré Brosseau et al. and entitled “Method for Recycling of ObsoletePrinted Circuit Boards,” which is hereby incorporated herein in itsentirety. Broadly, the method described in PCT/US2011/032675 comprisedat least one of (a), (b), (c), or any combination thereof:

(a) releasing a component from the PWB;(b) recovering a precious metal from the PWB and/or PWB component;(c) recovering a base metal from the PWB.

For the purposes of the present disclosure, “electronic waste” or“e-waste” corresponds to computers, computer monitors, televisionreceivers, electronic pads, cellular telephones, video cameras, digitalcameras, DVD players, video game consoles, facsimile machines, copiers,MP3 players, and similar products that have reached the end of theiruseful life or otherwise have been disposed of Electronic waste ore-waste includes the components contained within these well known itemssuch as printed wire boards and the components contained thereon (e.g.,transistors, capacitors, heat sinks, IC's, resistors, integratedswitches, chips and processors).

For the purposes of the general disclosure, the bare board is describedas comprising paper, low dielectric plastics, thin and flexibleplastics, ceramic/metal, fiberglass, epoxy and copper foil. As will beappreciated by the skilled artisan, “fiberglass” is a glass-reinforcedplastic or a glass fiber reinforced plastic and will correspond to anymaterial that comprises plastic and glass.

As used herein, “precious metals” include the metals gold, silver,platinum, palladium, rhodium, iridium, osmium, rhenium, ruthenium andalloys comprising same.

As used herein, “base metals” corresponds to iron, nickel, zinc, copper,aluminum, tungsten, molybdenum, tantalum, magnesium, cobalt, bismuth,cadmium, titanium, zirconium, antimony, manganese, beryllium, chromium,germanium, vanadium, gallium, hafnium, indium, niobium, rhenium,thallium, alloys comprising same, and combinations thereof.

As used herein, “copper” corresponds to Cu(0) metal as well as alloyscomprising Cu(0).

“Substantially devoid” is defined herein as less than 2 wt. %,preferably less than 1 wt. %, more preferably less than 0.5 wt. %, andmost preferably less than 0.1 wt. %. “Devoid” corresponds to 0 wt. %.

As used herein, “about” is intended to correspond to ±5% of the statedvalue.

As defined herein, “complexing agent” includes those compounds that areunderstood by one skilled in the art to be complexing agents, chelatingagents, sequestering agents, and combinations thereof. Complexing agentswill chemically combine with or physically associate with the metal atomand/or metal ion to be removed using the compositions described herein.

For the purposes of the present description, “printed wire boards” and“printed circuit boards” are synonymous and may be used interchangeably.

As used herein, the term “separation” corresponds to the completeremoval of the component(s) from the PWB or the partial separation ofthe component(s) from the PWB, wherein the partial separation of thecomponent from the PWB corresponds to the weakening of the solderholding the component(s) to the PWB and the remainder of the separationmay be carried out by another method.

As used herein, “to remove” lead- or tin-containing solder relative toprecious metals, base metals and/or tantalum-containing metals meansthat at least a portion of the lead- or tin-containing solder metal ismechanically removed or the lead- or tin-containing solder metal or ionsare substantially dissolved or otherwise solubilized in a removalcomposition, preferably dissolved, while other metals are notmechanically removed, substantially dissolved or otherwise solubilized.“Substantially dissolved” is defined herein more than 95 wt. % of thematerial originally present is dissolved or otherwise solubilized,preferably more than 98 wt. %, more preferably more than 99 wt. %, andmost preferably more than 99.9 wt. %. “Not substantially dissolved” isdefined herein less than 5 wt. % of the material originally present isdissolved or otherwise solubilized, preferably less than 2 wt. %, morepreferably less than 1 wt. %, and most preferably less than 0.1 wt. %.

As used herein, the term “leaches” corresponds to the complete removalor extraction of the gold or other precious metals from the PWB and/orPWB component into the leaching composition or the partial removal orextraction of the gold or other precious metals from the PWB and/or PWBcomponent into the leaching composition. The gold or other preciousmetal is dissolved or otherwise solubilized in the leaching composition,preferably dissolved.

As defined herein, “crushing” the PWB and/or PWB components correspondsto any method that substantially exposes the gold and other preciousmetals of the PWB and/or PWB component to the leaching composition,e.g., cracking, pulverizing or shredding the PWB and/or PWB component.Preferably, the PWB components are cracked, thereby minimizing theamount of gold or other precious metals lost as a result of thepulverizing or shredding. Precious metals can be lost if scrap ispulverized wherein gold dust adheres to the separated stream and is lostin the magnetic fraction. Accordingly, crushing is further defined as aprocess whereby no more than 10% of the gold or other precious metalsare lost to processes such as pulverizing or shredding, preferably nomore than 5%, even more preferably no more than 2%. Moreover, crushingthe e-waste minimizes the risk to human health by minimizing the releaseof dusts containing hazardous metals and brominated flame retardants.

It is well understood to the skilled artisan that “iodine” correspondsto the I₂ molecule while “iodide” (I⁻) is an anion and is provided as asalt. Iodide salts include, but are not limited to, lithium iodide,sodium iodide, potassium iodide, ammonium iodide, calcium iodide,magnesium iodide, and tetraalkylammonium iodides, wherein the alkylgroups may be the same as or different from one another and are selectedfrom the group consisting of straight-chained C₁-C₆ alkyls (e.g.,methyl, ethyl, propyl, butyl, pentyl, hexyl) and branched C₁-C₆ alkyls.

As defined herein, “carbon” includes crystalline graphite, amorphousgraphite, graphene, pyrolytic graphite, graphite oxide, graphite fibers,carbon nanotubes, conductive carbon, graphitized carbon, or anycarbonaceous species that includes the alpha (hexagonally arrangedcarbon atoms) or beta (rhombohedrally arranged carbon atoms) form ofgraphite.

Compositions may be embodied in a wide variety of specific formulations,as hereinafter more fully described. In all such compositions, whereinspecific constituents of the composition are discussed in reference toweight percentage ranges including a zero lower limit, it will beunderstood that such constituents may be present or absent in variousspecific embodiments of the composition, and that in instances wheresuch constituents are present, they may be present at concentrations aslow as 0.001 weight percent, based on the total weight of thecomposition in which such constituents are employed.

A First Apparatus and Method for Selectively Removing Solder from a PWB

Components are typically attached to the surface of PWBs with a lead,tin or lead-tin solder, which usually comes in combinations of70Sn/30Pb, 60Sn/40Pb or 63Sn/37Pb. In certain applications Ag—Sn solderis used. Currently, the desoldering of PWBs for component removalinvolves heating the solder to melting temperature, whereby theliberated components separate from the PWB and the liquid solder iscollected. This method applied for recycling PWBs has two maindisadvantages: (i) as lead and tin are low-volatile metals, such heatingand melting will create a high level of polluting emissions to theambient air; and (ii) the heat will damage the components making themunacceptable for re-use.

The present inventors previously disclosed a method of separating aprinted wire board component from a printed wire board inPCT/US2011/032675 using compositions. Broadly, said method comprisedcontacting a first composition with the printed wire board toselectively remove the printed wire board component from said printedwire board, wherein the printed wire board component is attached to theprinted wire board using solder or some other affixing means. Althougheffective, the inventors sought to increase the efficiency of the firstcomposition for removing the PWB components from the PWB.

Towards that end, in one aspect, an apparatus for removing solder from asurface is described, wherein the apparatus comprises mechanical solderremoval means and chemical solder removal means (see, e.g., FIG. 1).Mechanical solder removal means include, but are not limited to, cuttingblades, abrasive materials (e.g., bonded materials comprising aluminumoxide, silicon carbide, tungsten carbide, or garnet, or coated materialssuch as sandpaper), grinders, high pressure water or any other meanswhereby at least a portion of the solder can be removed from thesurface. The mechanical solder removal means are preferably immersed ina liquid (e.g., water) and can further include an agitator such asbrushes, rakes, or blown gases or liquids that are arranged paralleland/or perpendicular to the PWB to assist in the removal of the solder.Preferably, the mechanical solder removal means comprise cutting bladesimmersed in water that are capable of mechanically removing at leastabout 25% of the solder, more preferably at least about 35% of thesolder and even more preferably at least about 45% of the solder. Thenumber of cutting blades can be in a range from about 1 to about 500,depending on the apparatus setup and throughput. This aspect isespecially useful for PWBs comprising components having lead-basedsolders.

Chemical solder removal means include any apparatus that exposes thesurface to a first composition to effectuate the chemical removal ofsolder therefrom. It should be appreciated that the exposure of thesurface to the first composition can be effectuated in any suitablemanner, e.g., by spraying the first composition on the surface, bydipping the surface in a volume of the first composition, by contactingthe surface with another material, e.g., a pad, or fibrous sorbentapplicator element, that has the first composition absorbed thereon, bycontacting the surface with a recirculating composition, or by any othersuitable means, manner or technique, by which the first composition isbrought into contact with the material(s) to be removed. In a preferredembodiment, the surface is dipped in a volume of the first composition,wherein the volume can be substantial enough that the entire PWBcomprising the surface is immersed or alternatively, the PWB ispartially immersed such that only the surface comprising the solder isin the first composition (see, e.g., FIG. 2). Partial immersion isparticularly favored when the PWB has solder on only one side of theboard. In FIG. 2, the surface of the PWB comprising the solder isimmersed, not the whole board. It should be appreciated that the levelof liquid relative to the PWB thickness in FIG. 2 is just for visualdemonstration and may vary as readily determined by the skilled artisan.Further, the “platform” illustrated in FIG. 2 is merely intended toelevate the PWB above the bottom of the container and is not limited torollers (as shown), but can include a static flat surface (both solid orwith pores or holes), a belt, a scaffold, protuberances (having curved,pointed or flat peaks), or any other means whereby the PWB can be raisedabove the bottom of the container. The chemical solder removal means canfurther include an agitator such as brushes, rakes, or blown gases orliquids that are arranged parallel and/or perpendicular to the PWB toassist in the removal of the solder.

In one embodiment of the first aspect, as shown in FIG. 3, an apparatusfor removing solder from a surface of a printed wire board (PWB)comprises:

a mechanical solder remover;a chemical solder remover;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB movesautomatically or manually from the mechanical solder remover to thechemical solder remover to the rinsing module and to the drying module.In a particularly preferred embodiment, the PWB moves on a conveyerbelt, conveying rollers, or conveying wheels through the apparatus.

In another embodiment of the first aspect, as shown in FIG. 3, anapparatus for removing solder from a surface of a printed wire board(PWB) comprises:

a mechanical solder remover;a chemical solder remover comprising a container for a first compositionand at least one agitator,wherein the PWB is partially immersed in the first composition;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB movesautomatically from the mechanical solder remover to the chemical solderremover to the rinsing module and to the drying module. In aparticularly preferred embodiment, the PWB moves on a conveyer belt,conveying rollers, or conveying wheels through the apparatus.Preferably, the agitator comprises at least one brush, rake, or blowngases or liquids.

In another embodiment of the first aspect, as shown in FIG. 3, anapparatus for removing solder from a surface of a printed wire board(PWB) comprises:

a mechanical solder remover, comprising at least one blade and at leastone agitator for the mechanical removal of solder from the surface;a chemical solder remover comprising a container for a first compositionand at least one agitator;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB movesautomatically from the mechanical solder remover to the chemical solderremover to the rinsing module and to the drying module. In aparticularly preferred embodiment, the PWB moves on a conveyer belt,conveying rollers, or conveying wheels through the apparatus.Preferably, the agitator comprises at least one brush, rake, or blowngases or liquids

In still another embodiment of the first aspect, as shown in FIG. 3, anapparatus for removing solder from a surface of a printed wire board(PWB) comprises:

a mechanical solder remover, comprising at least one blade and at leastone agitator for the mechanical removal of solder from the surface;a chemical solder remover comprising a container for a first compositionand at least one agitator,wherein the PWB is partially immersed in the first composition;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB movesautomatically from the mechanical solder remover to the chemical solderremover to the rinsing module and to the drying module. In aparticularly preferred embodiment, the PWB moves on a conveyer belt,conveying rollers, or conveying wheels through the apparatus.Preferably, the agitator comprises at least one brush, rake, or blowngases or liquids

Some integrated circuits (ICs) are affixed to PWBs using epoxy (e.g.,North Bridge and South Bridge ICs and CPUs) and as such are not easilyremoved using the mechanical and chemical removal means describedherein. Accordingly, in another embodiment, the apparatus for removingsolder from a surface of a printed wire board (PWB) further comprises aheating module to soften the epoxy so that the ICs are easily removed tocomplete the removal of components and solder from the PWB.

Preferably, the heating modules 110 comprise a unit comprising means formoving the PWBs through a heating mechanism comprising agitation meansfor heating the epoxy and thereafter removing the epoxied ICs from thePWB. For example, FIG. 7 illustrates a top view of the heating modulecontemplated herein, wherein the means for moving the PWBs is a rollerchain 130, although other means of moving the PWBs are contemplatedincluding tracks, belts, and link chains. For example, the means formoving the PWBs can be a track with wheels that travel along the top ofthe track. The illustrated roller chain mechanism includes sprockets140, wherein one sprocket can be shaft driven and can be operated atvariable speeds, and the remaining sprockets can be free-wheels. Theroller chain or other means for moving the PWBs assumes a circumferencehaving an approximately rectangular shape, although alternativecircumference shapes are contemplated.

Attached to the roller chain or other means for moving the PWBs 150 areclips or clamps (see, 190 in FIGS. 8 and 9, which illustrate a frontview and a side view, respectively, of the heating module contemplatedherein) or other holding means, whereby the PWBs can be hung manually orautomatically to the roller chain 130. Preferably, the PWBs are clippedin an attachment region 170 just prior to entry into the heatingmechanism 120. The clips 190 are guided by a clip support clamp 210,which circumnavigates the roller chain or other means for moving PWBs.The PWBs are manually or automatically removed in disattachment region180, wherein the PWBs are unclipped from the roller chain. For example,a solenoid can be positioned in the disattachment region 180 such thatthe clip 190 opens and the PWB falls into a trough 230 that collects theboards.

Regarding the heating mechanism 120, it is illustrated as two equallysized, parallel units that can be heated, for example, using resistanceheating coils. Depending on the specific material to be removed, theheating mechanism 120 can be heated to the appropriate temperature, andthe PWBs can be moved through. By maintaining the temperature less thanthe melting point of the epoxy, the epoxy can be softened without thesimultaneous release of harmful or poisonous vapors. Thus for example,the heating mechanism 120 can be heated to temperatures that arepreferably in a range from about 100 to about 400° C. Most preferably,the temperature is set at least 1° C. to about 20° C. below the meltingpoint of the solder or epoxy to be removed. It should be appreciatedthat the region comprising the heating mechanism can be vented and theair scrubbed or filtered as readily understood by the person skilled inthe art.

Referring to FIG. 9, brushes 220 are positioned within the heatingmechanism such that following the softening of the epoxy, the epoxied ICcan be easily brushed off the PWB chip. Other positions for brushes 220are also envisioned, for example, outside the heating mechanism 120.Preferably, the brushes 220 have stainless steel bristles. Alternativesto brushes include, but are not limited to, high pressure gases orliquids, rakes, sonic energy and laser energy. In one particularembodiment, the heating mechanism 120 preferably includes means suchthat the heaters and brushes can be pushed in or retracted from the PWB.For example, the heaters and brushes can be pushed in or retractedmechanically, pneumatically, hydraulically or electromagnetically.

In practice, the PWBs 150 are attached to the roller chain in theattachment region and then enter the heating mechanism 120, whereby thetemperature is less than the melting point of the epoxy. Simultaneously,the brushes 220 remove the epoxied ICs from the PWBs 150, and the ICsdrop into a parts drawer 200. The PWBs minus ICs exit the heatingmechanism 120 and are immediately cooled, for example at roomtemperature. As the PWBs travel along the roller chain, thedisattachment region 180 is reached and the PWBs are unclipped and dropinto the open trough 230. The ICs and/or PWBs are subsequently moved,manually or automatically (e.g., conveyed) to the chemical solderremoval means.

Accordingly, the heating module apparatus for removing epoxiedcomponents from a PWB comprises: a heating mechanism and means formoving the PWBs through the heating mechanism, wherein the heatingmechanism comprises agitation means for removing the components once theepoxy has been softened so that the component can be removed from thePWB. In one embodiment, the agitation means comprise brushes and themeans for moving the PWBs through the heating mechanism comprises aroller chain. The PWB can be hung from the roller chain using clips orother clamping means. In a particular preferred embodiment, the heatingmechanism is maintained at least 1° C. to about 20° C. below the meltingpoint of the epoxy.

It is further contemplated that subsequent to the heating and removal ofthe epoxy-coated IC that the PWB can be re-introduced to the chemicalsolder remover, the rinsing module, and the drying module, as shown asan option in FIG. 3.

Accordingly, in another embodiment of the first aspect, as shown in FIG.3, an apparatus for removing solder from a surface of a printed wireboard (PWB) comprises:

a mechanical solder remover;a chemical solder remover;a heating module;a rinsing module; anda drying module.

Preferably, the apparatus is designed such that the PWB movesautomatically or manually from the mechanical solder remover to thechemical solder removal to the rinsing module and to the drying module.The heating module can be positioned between the chemical solder removerand the rinsing module or alternatively, the heating module can bepositioned after the drying module. It should be appreciated that if theheating module is positioned after the drying module, that the surfaceis preferably rinsed and dried again, either by directing the PWB intothe same rinsing and drying modules (as shown schematically in FIG. 3)or alternatively, by directing the PWB to a second rinsing module and asecond drying module. It is further contemplated that subsequent to theheating and removal of the epoxy-coated IC that the PWB can bere-introduced to the chemical solder remover, the rinsing module, andthe drying module, as shown as an option in FIG. 3. In a particularlypreferred embodiment, the PWB moves on a conveyer belt, conveyingrollers, or conveying wheels through the apparatus. Preferably, themechanical solder remover comprises at least one blade and at least oneagitator for the mechanical removal of solder from the surface.Preferably, the chemical solder remover comprises a container for afirst composition and at least one agitator, wherein the PWB ispartially immersed in the first composition. Preferably, the agitatorcomprises at least one brush, rake, or blown gases or liquids.

In each case, the rinsing module comprises means of rinsing the PWB toremove the first composition therefrom. It should be appreciated thatthe rinsing of the surface can be effectuated in any suitable manner,e.g., by spraying a rinsing composition on the surface, by dipping thesurface in a volume of the rinsing composition, by contacting thesurface with another material, e.g., a pad, or fibrous sorbentapplicator element, that has the rinsing composition absorbed thereon,by contacting the surface with a recirculating rinsing composition, orby any other suitable means, manner or technique, by which the rinsingcomposition is brought into contact with the material(s) to be removed.Preferably, the rinsing composition comprises water.

In each case, the drying module comprises means to dry the PWB.Preferred drying means include, but are not limited to, nitrogen gas,isopropanol, regenerative air, hot air or SEZ (spin process technology).

It should be appreciated that each embodiment of the apparatus canfurther comprise a component collector positioned subsequent to drying.

In a second aspect, the apparatus of the first aspect is used in aprocess of removing solder from the surface of a printed wire board(PWB), said process generally comprising removing at least a portion ofthe solder using mechanical solder removal means, and removing at leasta portion of the solder using chemical solder removal means. This aspectis especially useful for PWBs comprising components having lead-basedsolders. Preferably, at least about 25% of the solder is removed usingthe mechanical solder removal means, more preferably at least about 35%of the solder and even more preferably at least about 45% of the solder.Preferably, at least about 90% of the solder is removed using theprocess, more preferably at least about 95% of the solder, and morepreferably at least about 99% of the solder.

In one embodiment of the second aspect, a process of removing solderfrom the surface of the PWB comprises:

-   -   removing at least a portion of the solder using a mechanical        solder remover, wherein the mechanical solder remover comprises        at least one blade and at least one agitator for the mechanical        removal of solder from the surface; and        removing at least a portion of the solder using a chemical        solder remover.        The process can further comprise rinsing and drying of the PWB.        Preferably, the agitator comprises at least one brush, rake, or        blown gases or liquids.

In another embodiment of the second aspect, a process of removing solderfrom the surface of the PWB comprises:

removing at least a portion of the solder using a mechanical solderremover; andremoving at least a portion of the solder using a chemical solderremover, wherein the chemical solder remover comprises a container for afirst composition and at least one agitator, wherein the PWB ispartially immersed in the first composition.The process can further comprise rinsing and drying of the PWB.Preferably, the agitator comprises at least one brush, rake, or blowngases or liquids.

In still another embodiment of the second aspect, a process of removingsolder from the surface of the PWB comprises:

removing at least a portion of the solder using a mechanical solderremover, wherein the mechanical solder remover comprises at least oneblade and at least one agitator for the mechanical removal of solderfrom the surface; andremoving at least a portion of the solder using a chemical solderremover, wherein the chemical solder remover comprises a container for afirst composition and at least one agitator, wherein the PWB ispartially immersed in the first composition.The process can further comprise rinsing and drying of the PWB.Preferably, the agitator comprises at least one brush, rake, or blowngases or liquids.

The process of the second aspect can further comprises heating thesurface of the PWB to remove epoxy-coated components. Accordingly, inyet another embodiment of the second aspect, a process of removingsolder from the surface of the PWB comprises:

removing at least a portion of the solder using a mechanical solderremover;removing at least a portion of the solder using a chemical solderremover; andremoving epoxy-covered components using heating means.The process can further comprise rinsing and drying of the PWB.Preferably, the mechanical solder remover comprises at least one bladeand at least one agitator for the mechanical removal of solder from thesurface. Preferably, the chemical solder remover comprises a containerfor a first composition and at least one agitator, wherein the PWB ispartially immersed in the first composition. Preferably, the agitatorcomprises at least one brush, rake, or blown gases or liquids.

Advantageously, the apparatus of the first aspect and the process of thesecond aspect provide a more environmentally-friendly way to removecomponents and solder from waste PWBs. The processes can be carried outat process temperatures less than about 35° C., thus eliminating emittedlead vapors and the need for venting and scrubbing of large amounts ofair. Further, because the mechanical solder removal is preferentiallycarried out in a liquid (e.g., the blades are immersed in water), thereis no dangerous lead-containing dust generated. Further, advantagesassociated with partial immersion of the PWB in the first compositioninclude, but are not limited to, less wet chemicals are consumed, lesswet chemicals need to be disposed of, and less rinsing composition isused. In addition, preferably the apparatus is fully automated and thePWBs are conveyed from module to module. The process for removing solderfrom the surface of the PWBs results in the separation of electroniccomponents from the surface of PWBs, selectively removing the soldermetals while the precious and base metals and the exposed epoxy ofprinted circuit laminate are unaffected. The apparatus and processprovides a fast and economically efficient process forrecycling/reworking waste PWBs, including reclamation of electroniccomponents and forming a stream of more easily recyclable bare boardscontaining only copper, fiberglass reinforced epoxy andgold/nickel/copper plating.

The first composition is formulated to selectively remove the solderrelative to precious metals, tantalum-containing metals, and/or basemetals that are simultaneously present on said PWB. Preferably, thesolder comprises lead, tin, or a combination of lead and tin. In use ofthe compositions described herein for removing lead and/ortin-containing materials from PWB's having same thereon, the firstcomposition typically is contacted with the surface for a time of fromabout 5 sec to about 180 minutes, preferably about 1 min to 60 min, andmost preferably about 5 minutes to about 45 minutes at temperature in arange of from about 20° C. to about 85° C., preferably in a range fromabout 20° C. to about 40° C. Such contacting times and temperatures areillustrative, and any other suitable time and temperature conditions maybe employed that are efficacious to remove the solder to be removed fromthe PWB.

In one embodiment, the first composition comprises, consists of, orconsists essentially of at least one oxidizing agent. The firstcomposition may further comprise at least one lead and/or tin complexingagent, at least one organic solvent, and/or at least one passivatingagent for passivating the precious metals, tantalum-containing metals,and/or base metals. Accordingly, in one embodiment, the firstcomposition comprises, consists of, or consists essentially of at leastone lead and/or tin complexing agent in combination with at least oneoxidizing agent. In another embodiment, the first composition comprises,consists of, or consists essentially of at least one lead and/or tincomplexing agent, at least one oxidizing agent, and at least onepassivating agent for passivating the precious metals,tantalum-containing metals, and/or base metal materials. In stillanother embodiment, the first composition comprises, consists of, orconsists essentially of at least one lead and/or tin complexing agent,at least one oxidizing agent, and at least organic solvent. In yetanother embodiment, the first composition comprises, consists of, orconsists essentially of at least one lead and/or tin complexing agent,at least one oxidizing agent, at least one organic solvent, and at leastone passivating agent for passivating the precious metals,tantalum-containing metals, and/or base metal materials. In anotherembodiment, the first composition comprises, consists of, or consistsessentially of at least one oxidizing agent and at least one organicsolvent, wherein the first composition is substantially devoid of nitricacid, sulfuric acid, or combinations thereof. In still anotherembodiment, the first composition comprises, consists of, or consistsessentially of at least one oxidizing agent and at least one passivatingagent for passivating the precious metals, tantalum-containing metals,and/or base metals, wherein the first composition is substantiallydevoid of nitric acid, sulfuric acid, or combinations thereof. In yetanother embodiment, the first composition comprises, consists of, orconsists essentially of at least one oxidizing agent, at least oneorganic solvent, and at least one passivating agent for passivating theprecious metals and/or copper materials, wherein the first compositionis substantially devoid of nitric acid, sulfuric acid, or combinationsthereof. In still another embodiment, the first composition comprises,consists of, or consists essentially of at least one oxidizing agent, atleast one organic solvent, and at least one passivating agent forpassivating the precious metals, tantalum-containing metals, and/or basemetal materials, wherein the first composition is substantially devoidof sulfuric acid. These compositions possess the selectivity of leadand/or tin-containing materials relative to precious metals,tantalum-containing metals, and/or base metals thereby increasing theloading of the bath for the solder and increasing the bath-life of thefirst composition. Ion-exchange resins selective to lead and/or tin canbe used in combination with the first composition to further extend thelife of the bath. It should be appreciated that the first composition isan aqueous composition.

It should be appreciated by the skilled artisan that the firstcomposition described herein represents just one version of the firstcomposition of the process of the second aspect. Other compositions arecontemplated for use in the process of the second aspect, as readilydetermined by one skilled in the art.

Oxidizing agents are included in the composition to oxidize the metalsto be removed into an ionic form and accumulate highly soluble salts ofdissolved metals. Oxidizing agents contemplated herein include, but arenot limited to, ozone, nitric acid (HNO₃), bubbled air,cyclohexylaminosulfonic acid, hydrogen peroxide (H₂O₂), oxone (potassiumperoxymonosulfate, 2KHSO₅.KHSO₄.K₂SO₄), ammonium polyatomic salts (e.g.,ammonium peroxomonosulfate, ammonium chlorite (NH₄ClO₂), ammoniumchlorate (NH₄ClO₃), ammonium iodate (NH₄IO₃), ammonium perborate(NH₄BO₃), ammonium perchlorate (NH₄ClO₄), ammonium periodate (NH₄IO₃),ammonium persulfate ((NH₄)₂S₂O₈), ammonium hypochlorite (NH₄ClO)),sodium polyatomic salts (e.g., sodium persulfate (Na₂S₂O₈), sodiumhypochlorite (NaClO)), potassium polyatomic salts (e.g., potassiumiodate (KIO₃), potassium permanganate (KMnO₄), potassium persulfate,potassium persulfate (K₂S₂O₈), potassium hypochlorite (KClO)),tetramethylammonium polyatomic salts (e.g., tetramethylammonium chlorite((N(CH₃)₄)ClO₂), tetramethylammonium chlorate ((N(CH₃)₄)ClO₃),tetramethylammonium iodate ((N(CH₃)₄)IO₃), tetramethylammonium perborate((N(CH₃)₄)BO₃), tetramethylammonium perchlorate ((N(CH₃)₄)ClO₄),tetramethylammonium periodate ((N(CH₃)₄)IO₄), tetramethylammoniumpersulfate ((N(CH₃)₄)S₂O₈)), tetrabutylammonium polyatomic salts (e.g.,tetrabutylammonium peroxomonosulfate), peroxomonosulfuric acid, ureahydrogen peroxide ((CO(NH₂)₂)H₂O₂), peracetic acid (CH₃(CO)OOH), sodiumnitrate, potassium nitrate, ammonium nitrate, sulfuric acid, andcombinations thereof. Although not oxidizing agents per se, for the sakeof the present disclosure, oxidizing agents further includealkanesulfonic acids (e.g., methanesulfonic acid (MSA), ethanesulfonicacid, 2-hydroxyethanesulfonic acid, n-propanesulfonic acid,isopropanesulfonic acid, isobutenesulfonic acid, n-butanesulfonic acid,n-octanesulfonic acid), benzenesulfonic acid, benzenesulfonic acidderivatives (e.g., 4-methoxybenzenesulfonic acid,4-hydroxybenzenesulfonic acid, 4-aminobenzenesulfonic acid,4-nitrobenzenesulfonic acid, toluenesulfonic acid, hexylbenzenesulfonicacid, heptylbenzenesulfonic acid, octylbenzenesulfonic acid,nonylbenzenesulfonic acid, decylbenzenesulfonic acid,undecylbenzenesulfonic acid, dodecylbenzenesulfonic acid,tridecylbenzenesulfonic acid, tetradecylbenzene sulfonic acid,hexadecylbenzene sulfonic acid, 3-nitrobenzenesulfonic acid,2-nitrobenzenesulfonic acid, 2-nitronaphthalenesulfonic acid,3-nitronaphthalenesulfonic acid, 2,3-dinitrobenzenesulfonic acid,2,4-dinitrobenzenesulfonic acid, 2,5-dinitrobenzenesulfonic acid,2,6-dinitrobenzenesulfonic acid, 3,5-dinitrobenzenesulfonic acid,2,4,6-trinitrobenzenesulfonic acid, 3-aminobenzenesulfonic acid,2-aminobenzenesulfonic acid, 2-aminonaphthalenesulfonic acid,3-aminonaphthalenesulfonic acid, 2,3-diaminobenzenesulfonic acid,2,4-diaminobenzenesulfonic acid, 2,5-diaminobenzenesulfonic acid,2,6-diaminobenzenesulfonic acid, 3,5-diaminobenzenesulfonic acid,2,4,6-triaminobenzenesulfonic acid, 3-hydroxybenzenesulfonic acid,2-hydroxybenzenesulfonic acid, 2-hydroxynaphthalenesulfonic acid,3-hydroxynaphthalenesulfonic acid, 2,3-dihydroxybenzenesulfonic acid,2,4-dihydroxybenzenesulfonic acid, 2,5-dihydroxybenzenesulfonic acid,2,6-dihydroxybenzenesulfonic acid, 3,5-dihydroxybenzenesulfonic acid,2,3,4-trihydroxybenzenesulfonic acid, 2,3,5-trihydroxybenzene sulfonicacid, 2,3,6-trihydroxybenzenesulfonic acid, 2,4,5-trihydroxybenzenesulfonic acid, 2,4,6-trihydroxybenzenesulfonic acid,3,4,5-trihydroxybenzene sulfonic acid,2,3,4,5-tetrahydroxybenzenesulfonic acid,2,3,4,6-tetrahydroxybenzenesulfonic acid,2,3,5,6-tetrahydroxybenzenesulfonic acid,2,4,5,6-tetrahydroxybenzenesulfonic acid, 3-methoxybenzenesulfonic acid,2-methoxybenzenesulfonic acid, 2,3-dimethoxybenzene sulfonic acid,2,4-dimethoxybenzene sulfonic acid, 2,5-dimethoxybenzenesulfonic acid,2,6-dimethoxybenzenesulfonic acid, 3,5-dimethoxybenzenesulfonic acid,2,4,6-trimethoxybenzenesulfonic acid), and combinations thereof. Theoxidizing agents can include a combination of the any of the speciesdefined herein as oxidizing agent. The oxidizing agent may be introducedto the first composition at the manufacturer, prior to introduction ofthe first composition to the PWB, or alternatively at the PWB, i.e., insitu. Oxidizing agent is preferably present in the first composition anamount ranging from 0.1 to 90% by volume, more preferably from 10 to 60%by volume, and most preferably from 25 to 45% by volume. Preferably, theoxidizing agent comprises a peroxide compound, oxone, nitric acid and/ormethanesulfonic acid. Most preferably, the oxidizing agent comprisesmethanesulfonic acid.

When present, it is thought that an effective amount of nitric acidserve as an accelerator of the solder removal process. Accordingly, insome embodiments, the oxidizing agent in the first compositionpreferably comprises an alkane sulfonic acid (e.g., MSA) and nitricacid, wherein the alkane sulfonic acid is present in an amount rangingfrom 0.1 to 90 vol %, more preferably from 10 to 60 vol %, and mostpreferably from 25 to 45 vol %, and the nitric acid is present in anamount of about 0.1 to 80 vol %, preferably from about 1 to 45 vol %,and most preferably from 5 to 15 vol %.

The complexing agents are included to complex the ions produced by theoxidizing agent. Complexing agents contemplated herein include, but arenot limited to: β-diketonate compounds such as acetylacetonate,1,1,1-trifluoro-2,4-pentanedione, and1,1,1,5,5,5-hexafluoro-2,4-pentanedione; carboxylates such as formateand acetate and other long chain carboxylates; and amides (and amines),such as bis(trimethylsilylamide) tetramer. Additional chelating agentsinclude amines and amino acids (i.e. glycine, serine, proline, leucine,alanine, asparagine, aspartic acid, glutamine, valine, and lysine),citric acid, acetic acid, maleic acid, oxalic acid, malonic acid,succinic acid, phosphonic acid, phosphonic acid derivatives such ashydroxyethylidene diphosphonic acid (HEDP),1-hydroxyethane-1,1-diphosphonic acid, nitrilo-tris(methylenephosphonicacid), nitrilotriacetic acid, iminodiacetic acid, etidronic acid,ethylenediamine, ethylenediaminetetraacetic acid (EDTA), and(1,2-cyclohexylenedinitrilo)tetraacetic acid (CDTA), uric acid,tetraglyme, pentamethyldiethylenetriamine (PMDETA),1,3,5-triazine-2,4,6-thithiol trisodium salt solution,1,3,5-triazine-2,4,6-thithiol triammonium salt solution, sodiumdiethyldithiocarbamate, disubstituted dithiocarbamates(R¹(CH₂CH₂O)₂NR²CS₂Na) with one alkyl group (R²=hexyl, octyl, deceyl ordodecyl) and one oligoether (R¹(CH₂CH₂O)₂, where R¹=ethyl or butyl),ammonium sulfate, monoethanolamine (MEA), Dequest 2000, Dequest 2010,Dequest 2060s, diethylenetriamine pentaacetic acid, propylenediaminetetraacetic acid, 2-hydroxypyridine 1-oxide, ethylendiamine disuccinicacid (EDDS), N-(2-hydroxyethyl)iminodiacetic acid (HEIDA), sodiumtriphosphate penta basic, sodium and ammonium salts thereof, ammoniumchloride, sodium chloride, lithium chloride, potassium chloride,ammonium sulfate, hydrochloric acid, sulfuric acid, and combinationsthereof. Preferably, the complexing agent comprises HEDP, HEIDA, EDDS,sodium or ammonium salts thereof, sulfuric acid, or combinationsthereof. The amount of oxidizing agent to complexing agent is in avolume percent ratio range from about 10:1 to about 1:10, preferablyabout 5:1 to about 1:5, and even more preferably about 2:1 to about 1:2,wherein the oxidizing agent constituent is dilute and present in aweight percent of about 1 wt % to about 50 wt %, e.g., a volume of 30 wt% hydrogen peroxide, and the complexing agent constituent is dilute andpresent in a weight percent of about 1 wt % to about 50 wt %, e.g., avolume of 1 wt % HEDP. For example, the first composition can comprise 1part by volume of 30 wt % hydrogen peroxide plus 1 part by volume of a 1wt % complexing agent.

Passivating agents for passivating the precious metals,tantalum-containing metals, and/or base metals include, but are notlimited to, ascorbic acid, adenosine, L(+)-ascorbic acid, isoascorbicacid, ascorbic acid derivatives, citric acid, ethylenediamine, gallicacid, oxalic acid, tannic acid, ethylenediaminetetraacetic acid (EDTA),uric acid, 1,2,4-triazole (TAZ), triazole derivatives (e.g.,benzotriazole (BTA), tolyltriazole, 5-phenyl-benzotriazole,5-nitro-benzotriazole, 3-amino-5-mercapto-1,2,4-triazole,1-amino-1,2,4-triazole, hydroxybenzotriazole,2-(5-amino-pentyl)-benzotriazole, 1-amino-1,2,3-triazole,1-amino-5-methyl-1,2,3-triazole, 3-amino-1,2,4-triazole,3-mercapto-1,2,4-triazole, 3-isopropyl-1,2,4-triazole,5-phenylthiol-benzotriazole, halo-benzotriazoles (halo=F, Cl, Br or I),naphthotriazole), 4-amino-1,2,4-triazole (ATAZ), 2-mercaptobenzimidazole(MBI), 2-mercaptobenzothiazole, 4-methyl-2-phenylimidazole,2-mercaptothiazoline, 5-aminotetrazole (ATA),5-amino-1,3,4-thiadiazole-2-thiol, 2,4-diamino-6-methyl-1,3,5-triazine,thiazole, triazine, methyltetrazole, 1,3-dimethyl-2-imidazolidinone,1,5-pentamethylenetetrazole, 1-phenyl-5-mercaptotetrazole,diaminomethyltriazine, imidazoline thione, mercaptobenzimidazole,4-methyl-4H-1,2,4-triazole-3-thiol, 5-amino-1,3,4-thiadiazole-2-thiol,benzothiazole, tritolyl phosphate, imidazole, indiazole, benzoic acid,boric acid, malonic acid, ammonium benzoate, catechol, pyrogallol,resorcinol, hydroquinone, cyanuric acid, barbituric acid and derivativessuch as 1,2-dimethylbarbituric acid, alpha-keto acids such as pyruvicacid, adenine, purine, phosphonic acid and derivatives thereof,glycine/ascorbic acid, Dequest 2000, Dequest 7000, p-tolylthiourea,succinic acid, phosphonobutane tricarboxylic acid (PBTCA), sodiummolybdate, ammonium molybdate, salts of chromate (e.g., sodium,potassium, calcium, barium), sodium tungstate, salts of dichromate(e.g., sodium, potassium, ammonium), suberic acid, azaleic acid, sebacicacid, adipic acid, octamethylene dicarboxylic acid, pimelic acid,dodecane dicarboxylic acid, dimethyl malonic acid, 3,3-diethyl succinicacid, 2,2-dimethyl glutaric acid, 2-methyl adipic acid, trimethyl adipicacid, 1,3-cyclopentane dicarboxylic acid, 1,4-cyclohexane dicarboxylicacid, terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylicacid, 2,7-naphthalene dicaroxylic acid, 1,4-naphthalene dicarboxylicacid, 1,4-phenylenedioxy diacetic acid, 1,3-phenylenedioxy diaceticacid, diphenic acid, 4,4′-biphenyl dicarboxylic acid, 4,4′-oxydibenzoicacid, diphenylmethane-4,4′-dicarboxylic acid,diphenylsulfone-4,4′-dicarboxylic acid, decamethylene dicarboxylic acid,undecamethylene dicarboxylic acid, dodecamethylene dicarboxylic acid,orthophthalic acid, naphthalenedicarboxylic acid,paraphenylenedicarboxylic acid, trimellitic acid, pyromellitic acid,sodium phosphates (e.g., sodium hexametaphosphate), sodium silicates,amino acids and their derivatives such as 1-arginine, nucleoside andnucleobases such as adensosine and adenine, respectively, andcombinations thereof. Most preferably, the passivating agent comprisesBTA, ATAZ, TAZ, triazole derivatives, ascorbic acid, sodium molybdate,or combinations thereof. In a particularly preferred embodiment, thepassivating agent comprises sodium molybdate. More particularly, therole of the passivating agent is to reduce the composition's attack oncopper. This prevents the thin gold plating on the copper from beingundercut and lost as the copper dissolves, and it keeps such platingsafe for a further gold extraction process. When present, the amount ofpassivating agent is in a range from about 0.01 to 5 wt %, preferablyabout 0.1 wt % to about 1 wt %, based on the total weight of the firstcomposition.

Although not wishing to be bound by theory, it is thought that organicsolvents enhance the metal etch rates by wetting the surface of themicroelectronic device structure. Organic solvents contemplated hereininclude, but are not limited to, alcohols, ethers, pyrrolidinones,glycols, carboxylic acids, glycol ethers, amines, ketones, aldehydes,alkanes, alkenes, alkynes, carbonates, and amides, more preferablyalcohols, ethers, pyrrolidinones, glycols, carboxylic acids, and glycolethers such as methanol, ethanol, isopropanol, butanol, and higheralcohols (including diols, triols, etc.), tetrahydrofuran (THF),N-methylpyrrolidinone (NMP), cyclohexylpyrrolidinone,N-octylpyrrolidinone, N-phenylpyrrolidinone, methyl formate, dimethylformamide (DMF), dimethylsulfoxide (DMSO), tetramethylene sulfone(sulfolane), diethyl ether, phenoxy-2-propanol (PPh), propriopheneone,ethyl lactate, ethyl acetate, ethyl benzoate, acetonitrile, acetone,ethylene glycol, propylene glycol, dioxane, butyryl lactone, butylenecarbonate, ethylene carbonate, propylene carbonate, dipropylene glycol,amphiphilic species (diethylene glycol monomethyl ether, triethyleneglycol monomethyl ether, diethylene glycol monoethyl ether, triethyleneglycol monoethyl ether, ethylene glycol monopropyl ether, ethyleneglycol monobutyl ether, diethylene glycol monobutyl ether (i.e., butylcarbitol), triethylene glycol monobutyl ether, ethylene glycol monohexylether, diethylene glycol monohexyl ether, ethylene glycol phenyl ether,propylene glycol methyl ether, dipropylene glycol methyl ether (DPGME),tripropylene glycol methyl ether, dipropylene glycol dimethyl ether,dipropylene glycol ethyl ether, propylene glycol n-propyl ether,dipropylene glycol n-propyl ether (DPGPE), tripropylene glycol n-propylether, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether,tripropylene glycol n-butyl ether, propylene glycol phenyl ether, andcombinations thereof), branched non-fluorinated ether-linkage carboxylicacids (CH₃CH₂)_(n)O(CH₂)_(m)COOH, where n=1 to 10 and m=1 to 10),unbranched non-fluorinated ether-linkage carboxylic acids(CH₃CH₂)_(n)O(CH₂)_(m)COOH, where n=1 to 10 and m=1 to 10), branchednon-fluorinated non-ether linkage carboxylic acids (CH₃(CH₂)_(n)COOH,where n=1 to 10), unbranched non-fluorinated non-ether linkagecarboxylic acids (CH₃(CH₂)_(n)COOH, where n=1 to 10), dicarboxylicacids, tricarboxylic acids, and combinations thereof. Preferably, theorganic solvent comprises diethylene glycol monobutyl ether, dipropyleneglycol propyl ether, propylene glycol, or mixtures thereof. Whenpresent, the amount of organic solvent is in a range from about 0.01 wt% to about 25 wt %, preferably about 0.1 wt % to about 10 wt %, and mostpreferably about 0.1 wt % to about 5 wt %, based on the total weight ofthe first composition.

Typically hydrogen peroxide decomposes upon exposure to organics ormetals, thus, compositions that contain hydrogen peroxide have a shortshelf-life and thus must be mixed at the point of use. Due to the lackof infrastructure at some user sites, point of mix use is not an optionbecause of a lack of proper plumbing and chemical delivery systems,which add cost to a manufacturing plant. Advantageously, when the firstcomposition comprises the lead and/or tin complexing agent incombination with at least one oxidizing agent, the oxidizing agent isstabilized and thus can be pre-mixed, although it should be appreciatedthe said complexing agent and the at least one oxidizing agent may stillbe mixed at the point of use.

In another embodiment, the first composition comprises, consists of, orconsists essentially of: at least one oxidizing agent; optionally atleast one lead and/or tin complexing agent; optionally at least oneorganic solvent; optionally at least one passivating agent forpassivating the precious metals, tantalum-containing metals, and/or basemetals; and solder material. Preferably, the solder material compriseslead and/or tin-containing materials. The lead and/or tin-containingmaterials may be lead and/or tin ions dissolved and/or suspended in thecomposition described herein.

In still another embodiment, when the first composition includes nitricacid, the composition can further comprise ammonium sulfamate orsulfamic acid. The sulfamic ions are thought to stabilize the nitricacid and to suppress the evolution of toxic NO_(x) fumes. When present,the amount of sulfamate ion is in a range from about 0.1 to 20 wt %,preferably of about 1 to 10 wt %, and most preferably of about 1 to 5 wt%, based on the total weight of the first composition.

In a particularly preferred embodiment, the first composition comprises,consists of, or consists essentially of MSA, at least one organicsolvent, and at least one passivating agent, wherein the composition issubstantially devoid of nitric acid, sulfuric acid, or combinationsthereof. In another particularly preferred embodiment, the firstcomposition comprises, consists of, or consists essentially of MSA, atleast one glycol ether, and at least one passivating agent, wherein thecomposition is substantially devoid of nitric acid, sulfuric acid, orcombinations thereof. In still another particularly preferredembodiment, the first composition comprises, consists of, or consistsessentially of MSA, at least one glycol ether, and sodium molybdate,wherein the composition is substantially devoid of nitric acid, sulfuricacid, or combinations thereof. Even more preferably, the firstcomposition comprises, consists of, or consists essentially of MSA,diethylene glycol monobutyl ether, sodium molybdate, and water, whereinthe composition is substantially devoid of nitric acid, sulfuric acid,or combinations thereof. In still another embodiment, the firstcomposition comprises, consists of, or consists essentially of MSA, atleast one organic solvent, and at least one passivating agent, whereinthe composition is substantially devoid of sulfuric acid. In yet anotherembodiment, the first composition comprises, consists of, or consistsessentially of MSA, nitric acid, ammonium sulfamate, BTA, diethyleneglycol monobutyl ether, and water, wherein the composition issubstantially devoid of sulfuric acid. In another embodiment, the firstcomposition comprises, consists of, or consists essentially of MSA,nitric acid, ammonium sulfamate, BTA and water, wherein the compositionis substantially devoid of sulfuric acid. Additional embodiments of thefirst composition include (i) a first composition comprising, consistingof or consisting essentially of MSA, nitric acid, BTA and water; (ii) afirst composition comprising, consisting of or consisting essentially ofMSA, nitric acid, TAZ and water; (iii) a first composition comprising,consisting of or consisting essentially of MSA, nitric acid,1-amino-1,2,4-triazole and water; (iv) a first composition comprising,consisting of or consisting essentially of MSA, nitric acid,1-amino-1,2,3-triazole and water; (v) a first composition comprising,consisting of or consisting essentially of MSA, nitric acid,1-amino-5-methyl-1,2,3-triazole and water; (vi) a first compositioncomprising, consisting of or consisting essentially of MSA, nitric acid,3-amino-1,2,4-triazole and water; (vii) a first composition comprising,consisting of or consisting essentially of MSA, nitric acid,3-mercapto-1,2,4-triazole and water; (viii) a first compositioncomprising, consisting of or consisting essentially of MSA, nitric acid,3-isopropyl-1,2,4-triazole and water; (ix) a first compositioncomprising, consisting of or consisting essentially of MSA, nitric acid,MBI and water; (x) a first composition comprising, consisting of orconsisting essentially of MSA, nitric acid, ATA and water; (xi) a firstcomposition comprising, consisting of or consisting essentially of MSA,nitric acid, 2,4-diamino-6-methyl-1,3,5-triazine and water; (xii) afirst composition comprising, consisting of or consisting essentially ofMSA, nitric acid, ascorbic acid and water; (xiii) a first compositioncomprising, consisting of or consisting essentially of MSA, nitric acid,sodium molybdate and water; and (xiv) a first composition comprising,consisting of or consisting essentially of MSA, nitric acid,3-amino-5-mercapto-1,2,4-triazole and water. Another first compositioncomprises, consists of, or consists essentially of sulfuric acid, oxoneand propylene glycol.

It was found that the detachment and liberation of electronic componentsfrom the surface of PWBs can be achieved without addition of ferricnitrate if nitric acid is used in the first composition. In addition,the first composition can be substantially devoid of at least one offluoride salts, other ferric salts, titanium (IV) salts, abrasivematerial, fluoroboric acid, and organic solvents including ethylenegroups, e.g., ethylene, diethylene, triethylene, etc., and other HAPorganic solvents. As used herein, “fluoride” species correspond tospecies including an ionic fluoride (F⁻) or covalently bonded fluorine.It is to be appreciated that the fluoride species may be included as afluoride species or generated in situ.

Advantageously, an easily recyclable chemical composition can beemployed in a closed-loop process generating minimal waste. For example,when the first composition includes MSA, the MSA is easily recycled. Forexample, if the first composition includes MSA, a glycol ether andsodium molybdate, and said composition is contacted with Pb/Sn solder,the resulting composition including the Pb/Sn metals can be recycled bypassing the composition through a carbon filter to remove the glycolether and electrowinned to reclaim the Pb and Sn. The remaining solutionincluding MSA can be reused. When no longer viable, the firstcomposition can be rendered essentially non-toxic by electrowinning thePb and Sn and neutralizing the excess acidity.

The first composition described can be used to selectively remove leadand/or tin-containing materials and are compatible with the PWBcomponents, for example, transistors, capacitors, heat sinks, IC's,resistors, integrated switches, processors, etc., as well as theprecious metals, tantalum-containing metals, and/or base metals exposedon said PWB. Furthermore, the first compositions are water soluble,non-corrosive, non-flammable and of low toxicity.

It should be appreciated that the first composition can be used at thepoint of use as formulated or following dilution with water. Preferably,the diluent is deionized water and the extent of dilution is about 1:1to about 10:1 (water to first composition concentrate).

The first composition described herein has pH in a range from about 1 toabout 12 and can be adjusted depending on the complexing agent used(when present). For example, when the complexing agent comprises HEDP,HEIDA or, salts thereof, the pH of the composition will be highlyacidic, e.g., in a range from about 1 to about 4. When the complexingagent comprises EDDS, the pH of the composition may be advantageouslydialed in by using different sodium salts of EDDS. For example,compositions comprising EDDS having three sodium ions will have a pH ina range from about 4 to about 8, preferably about 5 to about 7.Compositions comprising EDDS having four sodium ions will have a pH in arange from about 8 to about 12, preferably about 9 to about 11.

Preferred embodiments of the first compositions described herein includecompositions comprising, consisting or, or consisting essentially of (i)EDDS/H₂O₂, (ii) HEIDA/H₂O₂, and (iii) MSA, nitric acid, ammoniumsulfamate, BTA, diethylene glycol monobutyl ether and (iv) MSA, nitricacid, ATAZ.

The first compositions described herein are easily formulated by simpleaddition of the respective ingredients and mixing to homogeneouscondition. Furthermore, the first composition may be readily formulatedas single-package formulations or multi-part formulations that are mixedat or before the point of use, e.g., the individual parts of themulti-part formulation may be mixed at the tool or in a storage tankupstream of the tool. The concentrations of the respective ingredientsmay be widely varied in specific multiples of the composition, i.e.,more dilute or more concentrated, and it will be appreciated that thecompositions described herein can variously and alternatively comprise,consist or consist essentially of any combination of ingredientsconsistent with the disclosure herein.

It should be appreciated by the skilled artisan that the solder attaches“components” such as transistors, capacitors, resistors, heat sinks,integrated circuits, integrated switches, processors, chips, etc. to thePWB. Advantageously, the first composition can be used to remove solderto separate the components from additional PWB surfaces until the firstcomposition is saturated with lead and/or tin metals. With the removalof the solder, the components are released and said components may beseparated using an optical system into those that are reusable and canbe resold and those that can be further processed for disposal,reclamation of useful materials, etc. The composition used to remove thelead and/or tin solder may undergo electrowinning to reclaim pure leadand/or tin and/or alternatively can be processed using diffusiondialysis technology to concentrate the metal ions.

A Second Apparatus and Method for Selectively Removing Solder from a PWB

Some printed wire boards, for example those found in cell phones havingWiFi capabilities, often comprise components that are covered by acasing, e g, steel, affixed to the surface with solder, e.g., Ag—Sn.Mechanically removing the steel casing, e.g., cutting with blades is nota favored methodology. Accordingly, a method is needed to easily removethe steel casing and recycle the waste PWB.

Towards, that end, in a third aspect, an apparatus for removing solderfrom a surface is described, wherein the apparatus comprises a heatingmodule and chemical solder removal means (see, e.g., FIG. 4). Theapparatus of the third aspect is particularly useful for two-sided PWBs,odd-shaped PWBs, and/or PWBs comprising the aforementioned casing. Itshould be appreciated that the apparatus of the third aspect can be usedto remove casings from one-sided PWBs as well. The heating module isused to soften the solder and adhesives, epoxies and glues so that thecasing is easily removed from the PWB.

In one aspect, the heating modules 110 comprise a unit comprising meansfor moving the waste PWBs through a heating mechanism comprisingagitation means for removing the casings from the PWB once the solder issoftened. For example, FIG. 7 illustrates a top view of the heatingmodule contemplated herein, wherein the means for moving the waste PWBsis a roller chain 130, although other means of moving the waste PWBs arecontemplated including tracks, belts, and link chains. For example, themeans for moving the waste PWBs can be a track with wheels that travelalong the top of the track. The illustrated roller chain mechanismincludes sprockets 140, wherein one sprocket can be shaft driven and canbe operated at variable speeds, and the remaining sprockets can befree-wheels. The roller chain or other means for moving the waste PWBsassumes a circumference having an approximately rectangular shape,although alternative circumference shapes are contemplated.

Attached to the roller chain or other means for moving the waste PWBs150 are clips or clamps (see, 190 in FIGS. 8 and 9, which illustrate afront view and a side view, respectively, of the heating modulecontemplated herein) or other holding means, whereby the waste PWBs canbe hung manually or automatically to the roller chain 130. Preferably,the waste PWBs are clipped in an attachment region 170 just prior toentry into the heating mechanism 120. The clips 190 are guided by a clipsupport clamp 210, which circumnavigates the roller chain or other meansfor moving waste PWBs. The waste PWBs are manually or automaticallyremoved in disattachment region 180, wherein the PWBs are unclipped fromthe roller chain. For example, a solenoid can be positioned in thedisattachment region 180 such that the clip 190 opens and the waste PWBfalls into a trough 230 that collects the boards.

Regarding the heating mechanism 120, it is illustrated as two equallysized, parallel units that can be heated using resistance heating coils.Depending on the specific material to be removed, the heating mechanism120 can be heated to the appropriate temperature, and the waste PWBs canbe moved through. By maintaining the temperature less than the meltingpoint of the solder, the solder can be softened without the simultaneousrelease of harmful or poisonous vapors. Thus for example, the heatingmechanism 120 can be heated to temperatures that are preferably in arange from about 100 to about 400° C. Most preferably, the temperatureis set at least 1° C. to about 20° C. below the melting point of thesolder to be softened. It should be appreciated that the regioncomprising the heating mechanism can be vented and the air scrubbed orfiltered as readily understood by the person skilled in the art.

Referring to FIG. 9, brushes 220 are positioned within the heatingmechanism such that following the softening of the solder, the casingcan be easily brushed off the waste PWB chip. Preferably, the brushes220 have stainless steel bristles. Alternatives to brushes include, butare not limited to, high pressure gases or liquids, rakes, sonic energyand laser energy. The heating mechanism 120 preferably includes meanssuch that the heaters and brushes can be pushed in or retracted from thewaste PWB. For example, the heaters and brushes can be pushed in orretracted mechanically, pneumatically, hydraulically orelectromagnetically.

In practice, the waste PWBs 150 are attached to the roller chain in theattachment region and then enter the heating mechanism 120, whereby thetemperature is less than the melting point of the solder.Simultaneously, the brushes 220 remove the casings from the waste PWBs150, and the removed casings drop into a parts drawer 200. The wastePWBs minus the casings exit the heating mechanism 120 and areimmediately cooled, for example at room temperature. As the waste PWBstravel along the roller chain, the disattachment region 180 is reachedand the waste PWBs are unclipped and drop into the open trough 230. Thecasings and/or waste PWBs are subsequently moved, manually orautomatically (e.g., conveyed) to the chemical solder removal means.

Accordingly, the heating module apparatus for removing casing from awaste PWB comprises: a heating mechanism and means for moving the wastePWBs through the heating mechanism, wherein the heating mechanismcomprises agitation means for removing casing from the PWB once thesolder has been softened solder. In one embodiment, the agitation meanscomprise brushes and the means for moving the waste PWBs through theheating mechanism comprises a roller chain. The waste PWB can be hungfrom the roller chain using clips or other clamping means. In aparticular preferred embodiment, the heating mechanism is maintained atleast 1° C. to about 20° C. below the melting point of the solder.

Advantageously, the heating module can be used to remove Pb—Sn solder,Ag—Sn solder and epoxy, as necessary.

Referring to FIG. 10(A), a waste PWB can be seen having the metalcasings over the components and printed circuits. Subsequent to a 3-5minute heat treatment at temperatures about 200° C., the casings areeasily removed with brushes, to yield the waste PWB shown in FIG. 10(B).

Chemical solder removal means include any apparatus that exposes thesurface to a first composition to effectuate the chemical removal ofsolder therefrom. It should be appreciated that the exposure of thesurface to the first composition can be effectuated in any suitablemanner, e.g., by spraying the first composition on the surface, bydipping the surface in a volume of the first composition, by contactingthe surface with another material, e.g., a pad, or fibrous sorbentapplicator element, that has the first composition absorbed thereon, bycontacting the surface with a recirculating composition, or by any othersuitable means, manner or technique, by which the first composition isbrought into contact with the material(s) to be removed. In a preferredembodiment, the surface is dipped in a volume of the first composition,wherein the volume can be substantial enough that the waste PWBcomprising the surface is immersed. Full immersion is especiallypreferred when the PWB is non-planar in structure. Large vesselscomprising a perforated drum are also contemplated whereby large numbersof PWBs can be inserted in the vessels for chemical solder removal.Preferably, the vessels are agitated such that the first compositionflows past the surfaces of the PWBs. In addition, the casings can beimmersed in the first composition to remove residual solder. It shouldbe appreciated that the casings can be immersed in the same or adifferent first composition that the PWBs are immersed in. Referring toFIG. 11, a waste PWB without the metal casing is shown before (FIG.11(A)) and after (FIG. 11(B)) immersion in the first composition for5-10 minutes at 40° C.

In one embodiment of the third aspect, as shown in FIG. 4, an apparatusfor removing solder from a surface of a printed wire board (PWB)comprises:

a heating module;a chemical solder remover;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB movesautomatically or manually from the heating module to the chemical solderremover to the rinsing module and to the drying module. In aparticularly preferred embodiment, the PWB moves on a conveyer belt,conveying rollers, or conveying wheels through the apparatus.

In another embodiment of the third aspect, as shown in FIG. 4, anapparatus for removing solder from a surface of a printed wire board(PWB) comprises:

a heating module;a chemical solder remover comprising a container for a firstcomposition;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB movesautomatically or manually from the heating module to the chemical solderremover to the rinsing module and to the drying module. In aparticularly preferred embodiment, the PWB moves on a conveyer belt,conveying rollers, or conveying wheels through the apparatus.

In another embodiment of the third aspect, as shown in FIG. 4, anapparatus for removing solder from a surface of a printed wire board(PWB) comprises:

a heating module, comprising a heating mechanism and means for movingthe waste PWBs through the heating mechanism;a chemical solder remover;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB movesautomatically or manually from the heating module to the chemical solderremover to the rinsing module and to the drying module. In aparticularly preferred embodiment, the PWB moves on a conveyer belt,conveying rollers, or conveying wheels through the apparatus.Preferably, the heating module comprises agitation means comprisingbrushes and the means for moving the waste PWBs through the heatingmechanism comprises a roller chain. The waste PWB can be hung from theroller chain using clips or other clamping means. In a particularpreferred embodiment, the heating mechanism is maintained at least 1° C.to about 20° C. below the melting point of the solder or epoxy.

In still another embodiment of the third aspect, as shown in FIG. 4, anapparatus for removing solder from a surface of a printed wire board(PWB) comprises:

a heating module, comprising a heating mechanism and means for movingthe waste PWBs through the heating mechanism;a chemical solder remover comprising a container for a firstcomposition;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB movesautomatically or manually from the heating module to the chemical solderremover to the rinsing module and to the drying module. In aparticularly preferred embodiment, the PWB moves on a conveyer belt,conveying rollers, or conveying wheels through the apparatus.Preferably, the heating module comprises agitation means comprisingbrushes and the means for moving the waste PWBs through the heatingmechanism comprises a roller chain. The waste PWB can be hung from theroller chain using clips or other clamping means. In a particularpreferred embodiment, the heating mechanism is maintained at least 1° C.to about 20° C. below the melting point of the solder or epoxy.

In each case, the rinsing module comprises means of rinsing the PWB toremove the first composition therefrom. It should be appreciated thatthe rinsing of the surface can be effectuated in any suitable manner,e.g., by spraying a rinsing composition on the surface, by dipping thesurface in a volume of the rinsing composition, by contacting thesurface with another material, e.g., a pad, or fibrous sorbentapplicator element, that has the rinsing composition absorbed thereon,by contacting the surface with a recirculating rinsing composition, orby any other suitable means, manner or technique, by which the rinsingcomposition is brought into contact with the material(s) to be removed.Preferably, the rinsing composition comprises water.

In each case, the drying module comprises means to dry the PWB.Preferred drying means include, but are not limited to, nitrogen gas,isopropanol, regenerative air, hot air or SEZ (spin process technology).

In a fourth aspect, the apparatus of the third aspect is used in aprocess of removing solder from the surface of a printed wire board(PWB), said process generally comprising removing casing or epoxiedcomponents from the surface of the PWB using heat, and removing at leasta portion of the solder using chemical solder removal means. This aspectis especially useful for PWBs comprising casings that are affixed to thesurface using the Ag—Sn-based solder, but it can be used when Pb—Snsolders or epoxies are used as well. Preferably, the casing or epoxiedcomponents are removed using agitation means comprising brushes. In aparticular preferred embodiment, the heat is maintained at least 1° C.to about 20° C. below the melting point of the solder or epoxy. Aspreviously described, the “casing” corresponds to a covering, oftensteel in material, that covers components on the PWB. The casing istypically affixed to the PWB using a Ag—Sn-based solder.

In one embodiment of the fourth aspect, a process of removing solderfrom the surface of the PWB comprises:

removing a casing from a surface of the PWB using heat; andremoving at least a portion of the solder using a chemical solderremover.The process can further comprise rinsing and drying of the PWB. In aparticular preferred embodiment, the heat is maintained at least 1° C.to about 20° C. below the melting point of the solder or epoxy

In another embodiment of the fourth aspect, a process of removing solderfrom the surface of the PWB comprises:

removing a casing from a surface of the PWB using heat and at least oneagitator; andremoving at least a portion of the solder using a chemical solderremover comprising a container for a first composition.The process can further comprise rinsing and drying of the PWB.Preferably, the agitator comprises brushes. In a particular preferredembodiment, the heating mechanism is maintained at least 1° C. to about20° C. below the melting point of the solder or epoxy.

In still another embodiment of the fourth aspect, a process of removingsolder from the surface of the PWB comprises:

removing at least one casing and/or epoxied component from a PWB using aheating module, wherein the heating module comprises a heating mechanismand a means for moving the PWB through the heating mechanism;removing at least a portion of the solder using a chemical solderremover, wherein the chemical solder remover comprises a container for afirst composition and at least one agitator, wherein the PWB ispartially immersed in the first composition; andremoving at least a portion of a precious metal using a leachingcomposition.

Advantageously, the apparatus of the third aspect and the process of thefourth aspect provide a more environmentally-friendly way to removecomponents and solder from waste PWBs.

Although the solder can comprise some silver, e.g., 3.5 wt % to 10 wt %,the first composition, as introduced hereinabove, selectively removesthe solder relative to precious metals, tantalum-containing metals,and/or base metals that are simultaneously present on said PWB becausethe solder substantially comprises tin. In use of the compositionsdescribed herein for removing substantially tin-containing solder fromPWB's having same thereon, the first composition typically is contactedwith the surface for a time of from about 5 sec to about 180 minutes,preferably about 1 min to 60 min, and most preferably about 5 minutes toabout 45 minutes at temperature in a range of from about 20° C. to about85° C., preferably in a range from about 20° C. to about 40° C. Suchcontacting times and temperatures are illustrative, and any othersuitable time and temperature conditions may be employed that areefficacious to remove the solder to be removed from the PWB.

Apparatus and Method for Precious Metal Leaching from a PWB

In a fifth aspect, an apparatus for recycling a printed wire board (PWB)is described, said apparatus generally comprising precious metalleaching means.

The inventors previously introduced in International Patent ApplicationPCT/US2011/032675 a composition and a method of recovering preciousmetals, e.g., gold, from precious metal-containing materials, whereinsaid method comprised introducing the precious metal-containingmaterials to a leaching composition comprising triiodide. Said preciousmetal-containing materials include, but are not limited to, electronicwaste (e-waste) such as PWBs and/or PWB components. Preferably, theprecious metal comprises gold. The precious metal containing materialscould be added to the leaching composition as is, pulverized into apowder, shredded into pieces, crushed such that the hard shell (e.g.,plastic) is cracked and the metals contained therein exposed, or in anyother form so long as the metals contained in the precious metalcontaining materials are readily exposed for removal from the materials.

In use, the leaching compositions for leaching precious metals fromprecious metal containing materials were contacted with the preciousmetal containing materials for a time of from about 5 sec to about 180minutes, preferably about 1 min to 60 min, and most preferably about 5minutes to about 45 minutes at temperature in a range of from about 20°C. to about 60° C., preferably in a range from about 20° C. to about 40°C. Such contacting times and temperatures are illustrative, and anyother suitable time and temperature conditions may be employed that areefficacious to remove precious metals from the precious metal containingmaterials. In application, the leaching composition is contacted in anysuitable manner to the precious metal containing material, (e.g., PWBand/or PWB components), e.g., by spraying the composition on the PWBand/or PWB components, by dipping (in a volume of the composition) ofthe PWB and/or PWB components, by contacting the PWB and/or PWBcomponents with another material, e.g., a pad, or fibrous sorbentapplicator element, that has the composition absorbed thereon, or by anyother suitable means, manner or technique, by which a leachingcomposition is brought into contact with the PWB and/or PWB components.Preferably, the PWB and/or PWB components are fully immersed in a volumeof the leaching composition.

After the precious metal containing materials have been exposed to theleaching composition the leaching composition comprising the gold orother precious metals can be isolated from the PWBs and/or PWBcomponents and precipitates that may be present. Isolation techniquesinclude filtration, centrifugation, decanting, or a combination of anyof these. The precious metal can be liberated from the leachingcomposition as described in PCT/US2011/032675. For example, solid metalcan be obtained by reducing the gold or other precious metals in theleaching composition (e.g., with a reducing agent suitable for suchpurpose).

Although during the precious metal leaching process the dissolution ofbase metals is generally inhibited, some base metals can stillaccumulate in the composition after several repetitive leaching cycles.In order to remove these base metals, the leaching composition can beflowed through a packed column containing ion-exchange resins, where thedissolved base metals will be selectively captured, while the tri-iodideions and the dissolved precious metals will pass through. The resinsthat can be used for this purpose are commercially available, stronglyacidic cation exchangers (e.g., DOWEX ion exchange resins manufacturedby The Dow Chemical Company). The purification of the leachingcomposition by base metal removal need not be a part of each leachingcycle, but can be repeated as often as the solution becomes polluted tothe point that its effectiveness is negatively affected. The base metalscan also be removed via electroplating either during the leachingprocess or after the leaching process and gold plating. This allows theleaching chemistry to be recycled more times since base metal loading isreduced before gold leaching commences again.

As soon as the leaching process is over and the loaded tri-iodidesolution is separated from the leached material, the leached materialcan be rinsed (e.g., with water) to recover the leaching composition,which can contain very significant amounts of tri-iodide and dissolvedgold. When the leached material comprises PWBs, a bare board comprisingfiberglass, copper sheet and epoxy remains. The leaching composition maybe readily removed from the PWB to which it has previously been appliedusing a rinse composition. Preferably, the rinse composition compriseswater. Thereafter, the PWB may be dried using nitrogen or a spin-drycycle.

Accordingly, in one embodiment, the fifth aspect comprises an apparatusfor recycling a PWB and/or PWB component, said apparatus comprisingprecious metal removal means comprising:

a precious metal leaching module;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB and/or PWBcomponent moves automatically or manually from the precious metalleaching module to the rinsing module and to the drying module. In aparticularly preferred embodiment, the PWB and/or PWB component moves ona conveyer belt, conveying rollers, or conveying wheels through theapparatus.

In another embodiment, an apparatus for recycling a PWB and/or PWBcomponent is described, said apparatus comprising precious metal removalmeans comprising:

a precious metal leaching module comprising a container for a leachingcomposition comprising tri-iodide;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB and/or PWBcomponent moves automatically or manually from the precious metalleaching module to the rinsing module and to the drying module. In aparticularly preferred embodiment, the PWB and/or PWB component moves ona conveyer belt, conveying rollers, or conveying wheels through theapparatus.

In another embodiment, an apparatus for recycling a PWB and/or PWBcomponent is described, said apparatus comprising precious metal removalmeans comprising:

a crushing module;a precious metal leaching module comprising a container for a leachingcomposition comprising tri-iodide;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB and/or PWBcomponent moves automatically or manually from the precious metalleaching module to the rinsing module and to the drying module. In aparticularly preferred embodiment, the PWB and/or PWB component moves ona conveyer belt, conveying rollers, or conveying wheels through theapparatus.

In another embodiment, an apparatus for recycling a PWB and/or PWBcomponent is described, said apparatus comprising precious metal removalmeans comprising:

a crushing module;a precious metal leaching module comprising a container for a leachingcomposition comprising salt brine/acid mixtures or the firstcomposition;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB and/or PWBcomponent moves automatically or manually from the precious metalleaching module to the rinsing module and to the drying module. In aparticularly preferred embodiment, the PWB and/or PWB component moves ona conveyer belt, conveying rollers, or conveying wheels through theapparatus.

In each apparatus of the fifth aspect, the apparatus can optionallyinclude a heating module, e.g., analogous to that of the first aspect,wherein the PWB is directed to a heating module to soften epoxy in theevent any additional epoxy-coated components remain on the board so thatsaid components are easily removed. Heating modules can be easilyincorporated into the apparatus subsequent to the precious metalleaching module and preferably comprise vented ovens whereintemperatures in a range from about 100 to 400° C. can be achieved tosoften the ICs that are affixed to the PWB using epoxy. Agitators suchas brushes, rakes, or blown gases or liquids positioned within theheating module readily effectuate the removal of the components once theepoxy is softened. The vented ovens preferably include scrubbing meanssince lead vapors are likely a byproduct of the heating process.

The crushing module, when used, can be inline or crushing can beeffectuated separately and the crushed PWB and/or PWB componentsautomatically or manually fed into the apparatus. Crushing meansinclude, but are not limited to, means for pulverizing, means forshredding, and means for crushing the PWB and/or PWB components so thatthe hard shell (e.g., plastic) is cracked, as readily determined by theperson skilled in the art. Preferably, when PWBs are being processedthey are crushed to crack the board. Preferably, when PWB components arebeing processed they are pulverized into a powder.

In each case, the rinsing module comprises means of rinsing the PWBand/or PWB components to remove the leaching composition therefrom. Itshould be appreciated that the rinsing of the surface can be effectuatedin any suitable manner, e.g., by spraying a rinsing composition on thesurface, by dipping the surface in a volume of the rinsing composition,by contacting the surface with another material, e.g., a pad, or fibroussorbent applicator element, that has the rinsing composition absorbedthereon, by contacting the surface with a recirculating rinsingcomposition, or by any other suitable means, manner or technique, bywhich the rinsing composition is brought into contact with thematerial(s) to be removed. Preferably, the rinsing composition compriseswater.

In each case, the drying module comprises means to dry the PWB.Preferred drying means include, but are not limited to, nitrogen gas,isopropanol, regenerative air, hot air or SEZ (spin process technology).

The tri-iodide ion can be introduced in the leaching composition by anyknown method including, but not limited to: dissolution of iodine in anaqueous solutions of iodides (e.g., KI, NaI, NH₄I) or hydroiodic acid;in situ generation of iodine which reacts with excess iodide to formtriiodide; oxidation of aqueous solutions of iodides by nitric acid,ozone, hypochlorite and the like; and reaction of an iodide with aniodate in acidic media. Several are described at length below.

Iodine (I₂) is very expensive and has low solubility in water but it canbe generated in situ. Iodine in an aqueous solution of iodide is presentas the triiodide ioin. The process utilizes iodine to oxidize the goldwhile iodide contributes to solubilizing the oxidized gold by formationof a gold iodide complex.

In one embodiment, the leaching composition comprises, consists of, orconsists essentially of at least one oxidizing agent, at least oneiodide salt or hydroiodic acid and water. In another embodiment, theleaching composition comprises, consists of, or consists essentially ofat least one oxidizing agent, at least one iodide salt or hydroiodicacid, water, optionally at least one organic solvent, optionally atleast one metal passivating agent, optionally at least one surfactant,optionally at least one buffering agent. In another embodiment, theleaching composition comprises, consists of, or consists essentially ofat least one oxidizing agent, at least one iodide salt or hydroiodicacid, water, and at least one organic solvent. In still anotherembodiment, the leaching composition comprises, consists of, or consistsessentially of at least one oxidizing agent, at least one iodide salt orhydroiodic acid, water, and at least one metal passivating agent. Instill another embodiment, the leaching composition comprises, consistsof, or consists essentially of at least one oxidizing agent, at leastone iodide salt or hydroiodic acid, water, at least one metalpassivating agent, and at least one buffering agent. In still anotherembodiment, the leaching composition comprises, consists of, or consistsessentially of at least one oxidizing agent, at least one iodide salt orhydroiodic acid, water, and at least one surfactant. In yet anotherembodiment, the leaching composition comprises, consists of, or consistsessentially of at least one oxidizing agent, at least one iodide salt orhydroiodic acid, water, at least one organic solvent, and at least onemetal passivating agent. In yet another embodiment, the leachingcomposition comprises, consists of, or consists essentially of at leastone oxidizing agent, at least one iodide salt or hydroiodic acid, water,at least one organic solvent, and at least one surfactant. In yetanother embodiment, the leaching composition comprises, consists of, orconsists essentially of at least one oxidizing agent, at least oneiodide salt or hydroiodic acid, water, at least one surfactant, and atleast one metal passivating agent. In yet another embodiment, theleaching composition comprises, consists of, or consists essentially ofat least one oxidizing agent, at least one iodide salt or hydroiodicacid, water, at least one organic solvent, at least one surfactant, andat least one metal passivating agent. It is understood that the iodidesalt or hydroiodic acid and the oxidizing agent present in the leachingcomposition will react to form iodine in situ and iodide ion will be inexcess, resulting in the formation of triiodide. Accordingly, theleaching composition subsequent to the in situ reaction will comprise,consist of, or consist essentially of triiodide and water. In anotherembodiment, the leaching composition subsequent to the in situ reactionwill comprise, consist of, or consist essentially of triiodide, water,and at least one organic solvent. In still another embodiment, theleaching composition subsequent to the in situ reaction will comprise,consist of, or consist essentially of triiodide, water, and at least onepassivating agent. In still another embodiment, the leaching compositionsubsequent to the in situ reaction will comprise, consist of, or consistessentially of triiodide, water, and at least one surfactant. In yetanother embodiment, the leaching composition subsequent to the in situreaction will comprise, consist of, or consist essentially of triiodide,water, at least one organic solvent, and at least one passivating agent.In yet another embodiment, the leaching composition subsequent to the insitu reaction will comprise, consist of, or consist essentially oftriiodide, water, at least one organic solvent, and at least onesurfactant. In yet another embodiment, the leaching compositionsubsequent to the in situ reaction will comprise, consist of, or consistessentially of triiodide, water, at least one surfactant, and at leastone passivating agent. In yet another embodiment, the leachingcomposition subsequent to the in situ reaction will comprise, consistof, or consist essentially of triiodide, water, at least one organicsolvent, at least one surfactant, and at least one passivating agent.The leaching composition is formulated to selectively and substantiallyleach gold from the e-waste into a fraction that can be furtherprocessed to reclaim said gold. For example, in one embodiment, theleaching composition can be used to separate gold or other precious frombase metals, wherein the base metals remain as a solid.

Potential oxidizing agents were previously defined herein for use in thefirst composition. Preferably, the oxidizing agent in the leachingcomposition comprises oxone, sodium persulfate, ammonium persulfate,potassium persulfate, nitric acid, hydrogen peroxide, ferric chloride,ferric nitrate, or combinations thereof. Even more preferably, theoxidizing agent in the leaching composition comprises ammoniumpersulfate, sodium persulfate, nitric acid, periodic acid, oxone, sodiumhypochlorite, or combinations thereof. The amount of oxidizing agent inthe leaching composition is in a range from about 0.01 wt % to about 25wt %, preferably about 1 wt % to about 20 wt %, and most preferablyabout 1 wt % to about 10 wt %.

Iodide salts include, but are not limited to, lithium iodide, sodiumiodide, potassium iodide, ammonium iodide, calcium iodide, magnesiumiodide, and tetraalkylammonium iodides, wherein the alkyl groups may bethe same as or different from one another and are selected from thegroup consisting of straight-chained C₁-C₆ alkyls (e.g., methyl, ethyl,propyl, butyl, pentyl, hexyl) and branched C₁-C₆ alkyls. Preferably, theiodide salt comprises potassium iodide. Hydroiodic acid can be usedinstead of an iodide salt. The amount of iodide salt is in a range fromabout 0.1 wt % to about 50 wt %, preferably about 1 wt % to about 40 wt%, and most preferably about 10 wt % to about 35 wt %.

Potential organic solvents were previously defined herein for use in thefirst composition. Most preferably, when present, the organic solvent inthe leaching composition comprises an alcohol, diethylene glycolmonobutyl ether, propylene glycol, dipropylene glycol n-butyl ether,carbonates such as ethylene carbonate, and combinations thereof. Whenincluded, the amount of organic solvent in the leaching composition isin a range from about 0.01 wt % to about 20 wt %, preferably about 1 wt% to about 10 wt %, and most preferably about 1 wt % to about 5 wt %.

Potential passivating agents were previously defined herein for use inthe first composition. When included, the amount of passivating agent inthe leaching composition is in a range from about 0.01 wt % to about 10wt %, preferably about 0.05 wt % to about 5 wt %, and most preferablyabout 0.05 wt % to about 2 wt %.

Surfactants contemplated include, but are not limited to, acids andbases, non-ionic surfactants, anionic surfactants, cationic surfactants,zwitterionic surfactants, and combinations thereof. Preferred acidic orbasic surfactants include, but are not limited to, surfactants having anacid or base functionality (“head”) and a straight-chained or branchedhydrocarbon group (“tail”) and/or surfactants having an acidfunctionality (“head”) and a perfluorinated hydrocarbon group (“tail”).Preferred acid or base functionalities include phosphoric, phosphonic,phosphonic monoesters, phosphate monoesters and diesters, carboxylicacids, dicarboxylic acid monoesters, tricarboxylic acid mono- anddiesters, sulfate monoesters, sulfonic acids, amines, and salts thereof.The hydrocarbon groups preferably have at least 10, e.g., 10-20, carbonatoms (e.g., decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl,hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl), except thatsomewhat shorter hydrocarbon groups of 6-16 carbons (e.g. hexyl,2-ethylhexyl, dodecyl) are preferred where the molecule contains twoalkyl chains such as in phosphate diesters and phosphonate monoesters.The perfluorinated hydrocarbon groups preferably have 7-14 carbon atoms(e.g., heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl,tetradecyl). Preferred surfactants include decylphosphonic acid,dodecylphosphonic acid, tetradecylphosphonic acid, hexadecylphosphonicacid, bis(2-ethylhexyl)phosphate, octadecylphosphonic acid,perfluoroheptanoic acid, prefluorodecanoic acid,trifluoromethanesulfonic acid, phosphonoacetic acid,dodecylbenzenesulfonic acid, and dodecylamine.

Non-ionic surfactants contemplated include, but are not limited to,polyoxyethylene lauryl ether (Emalmin NL-100 (Sanyo), Brij 30, Brij 98),dodecenylsuccinic acid monodiethanol amide (DSDA, Sanyo),ethylenediamine tetrakis (ethoxylate-block-propoxylate) tetrol (Tetronic90R4), polyoxyethylene polyoxypropylene glycol (Newpole PE-68 (Sanyo),Pluronic L31, Pluronic 31R1), polyoxypropylene sucrose ether (SN008S,Sanyo), t-octylphenoxypolyethoxyethanol (Triton X100), Polyoxyethylene(9) nonylphenylether, branched (IGEPAL CO-250), polyoxyethylene sorbitolhexaoleate, polyoxyethylene sorbitol tetraoleate, polyethylene glycolsorbitan monooleate (Tween 80), sorbitan monooleate (Span 80),alkyl-polyglucoside, ethyl perfluorobutyrate,1,1,3,3,5,5-hexamethyl-1,5-bis[2-(5-norbornen-2-yl)ethyl]trisiloxane,monomeric octadecylsilane derivatives such as SIS6952.0 (Siliclad,Gelest), siloxane modified polysilazane such as PP1-SG10 Siliclad Glide10 (Gelest), silicone-polyether copolymers such as Silwet L-77 (SetreChemical Company), Silwet ECO Spreader (Momentive), and alcoholethoxylates (NatsurfrM 265, Croda).

Cationic surfactants contemplated include, but are not limited to,heptadecanefluorooctane sulfonic acid tetraethylammonium, stearyltrimethylammonium chloride (Econol TMS-28, Sanyo),4-(4-diethylaminophenylazo)-1-(4-nitrobenzyl)pyridium bromide,cetylpyridinium chloride monohydrate, benzalkonium chloride,benzethonium chloride benzyldimethyldodecylammonium chloride,benzyldimethylhexadecylammonium chloride, hexadecyltrimethylammoniumbromide, dimethyldioctadecylammonium chloride, dodecyltrimethylammoniumchloride, hexadecyltrimethylammonium p-toluenesulfonate,didodecyldimethylammonium bromide, di(hydrogenatedtallow)dimethylammonium chloride, tetraheptylammonium bromide,tetrakis(decyl)ammonium bromide, Aliquat® 336 and oxyphenonium bromide.The hydrocarbon groups preferably have at least 10, e.g., 10-20, carbonatoms (e.g., decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl,hexadecyl, heptadecyl, octadecyl, nonadecyl, eicosyl), except thatsomewhat shorter hydrocarbon groups of 6-20 carbons (e.g. hexyl,2-ethylhexyl, dodecyl) are preferred where the molecule contains twofunctionized alkyl chains such as in dimethyldioctadecylammoniumchloride, dimethyldihexadecylammonium bromide and di(hydrogenatedtallow)dimethylammonium chloride.

Anionic surfactants contemplated include, but are not limited to, sodiumpolyoxyethylene lauryl ether, sodium dihexylsulfosuccinate, dicyclohexylsulfosuccinate sodium salt, sodium 7-ethyl-2-methyl-4-undecyl sulfate(Tergitol 4), SODOSIL RM02, and phosphate fluorosurfactants such asZonyl FSJ.

Zwitterionic surfactants include, but are not limited to, ethylene oxidealkylamines (AOA-8, Sanyo), N,N-dimethyldodecylamine N-oxie, sodiumcocaminpropinate (LebonApl-D, Sanyo),3-(N,N-dimethylmyristylammonio)propanesulfonate, and(3-(4-heptyl)phenyl-3-hydroxypropyl)dimethylammoniopropanesulfonate.

Inorganic acids may be optionally added to of the leaching compositions.For example, the leaching composition may further include sulfuric,hydrochloric, hydrobromic, or hydroiodic acid.

The pH of the leaching composition is preferably about 3 to about 10,more preferably about 4 to about 8 and most preferably about 6 to about8. In a preferred embodiment, a buffering agent is added to maintain thepH of the leaching composition in the range from about 5 to about 8.Buffering agents are well known in the art and can include, for example,phosphate buffer such as monosodium phosphate/disodium phosphate ormonopotassium phosphate/dipotassium phosphate.

The leaching compositions are easily formulated by simple addition ofthe respective ingredients and mixing to homogeneous condition.Furthermore, the compositions may be readily formulated as multi-partformulations that are mixed at or before the point of use, e.g., theindividual parts of the multi-part formulation may be mixed at the toolor in a storage tank upstream of the tool. The concentrations of therespective ingredients may be widely varied in specific multiples of thecomposition, i.e., more dilute or more concentrated, and it will beappreciated that the compositions can variously and alternativelycomprise, consist or consist essentially of any combination ofingredients consistent with the disclosure herein.

Preferably, in one embodiment, the leaching composition comprises,consists of, or consists essentially of potassium iodide, sodiumpersulfate and water, more preferably about 20 wt % to about 30 wt %potassium iodide, about 4 wt % to about 10 wt % sodium persulfate andwater. In another embodiment, the leaching composition comprises,consists of, or consists essentially of potassium iodide, ammoniumpersulfate and water, more preferably about 20 wt % to about 30 wt %potassium iodide, about 4 wt % to about 10 wt % ammonium persulfate andwater. In yet another embodiment, the leaching composition comprises,consists of, or consists essentially of potassium iodide, sodiumpersulfate, BTA, and water. In yet another embodiment, the leachingcomposition comprises, consists of, or consists essentially of potassiumiodide, sodium persulfate, BTA, phosphate buffer, and water. In stillanother embodiment, the leaching composition comprises, consists of, orconsists essentially of potassium iodide, nitric acid and water. Inanother embodiment, the leaching composition comprises, consists of, orconsists essentially of potassium iodide, periodic acid, hydrochloricacid and water. The leaching composition in another embodimentcomprises, consists of, or consists essentially of potassium iodide,oxone and water. In still another embodiment, the leaching compositioncomprises, consists of, or consists essentially of potassium iodide,sodium hypochlorite, hydrochloric acid and water. In yet anotherembodiment, the leaching composition comprises, consists of, or consistsessentially of potassium iodide, in situ generated iodine and water. Theleaching compositions are substantially devoid of aqua regia andcyanide-containing components. Preferably, the leaching compositions arewater soluble, non-corrosive, non-flammable and of low toxicity.

It should be appreciated by the skilled artisan that once the gold orother precious metals are leached from the PWBs and/or PWB components,the remaining material(s) may be disposed of, recycled or undergofurther reclamation. Following the extraction/leaching of the gold orother precious metals into the leaching composition, the gold or otherprecious metals can be obtained by reducing the metal ions, as discussedat length in PCT/US2011/032675. Preferably, the reducing agent is aso-called environmentally friendly chemical. Preferred reducing agentsinclude, but are not limited to, ascorbic acid, diethyl malonate, sodiummetabisulfite, polyphenon 60 (P60, green tea extract), glucose, andsodium citrate. For example, as introduced in U.S. Provisional PatentApplication No. 61/375,273 filed on Aug. 20, 2010 and entitled“Sustainable Process for Reclaiming Precious Metals and Base Metals frome-Waste,” which is hereby incorporated by reference herein in itsentirety, ascorbic acid introduced to a composition comprising Au³⁺ ionsat pH 1 produces highly pure gold metal. Sodium metabisulfite (SMB) canbe added to a composition comprising Au³⁺ ions at pH 1 or pH 7 andproduce highly pure gold metal. Alternatively, the gold ions can beconverted to gold metal via electrowinning or electrochemicaltechniques. Any suitable means can be used to remove the precipitatedgold. Settling and decanting, filtering the solution through a filterpress or centrifuging are convenient procedures for such removal.

It is also contemplated that the leaching composition can be used tosimultaneously separate carbon and precious metals from the PWB solidmaterials. Specifically, the precious metal leaching module can furthercomprise means for froth flotation, wherein the froth flotation is usedto separate the carbon from the other materials. Froth flotation employsa frothing agent, which generates a stable foamy layer (the “froth”) ontop of an aqueous column, and a collecting agent which serves toconcentrate the carbon in the froth layer. In general, the method ofseparating carbon from the e-waste comprises contacting the e-wastecomprising said carbon and precious metals with the leachingcomposition, said leaching composition comprising triiodide as describedherein and at least one frothing agent and at least one collecting agentto form a mixture; generating a froth layer and a liquid layer; andseparating the froth layer from a liquid layer, wherein the froth layercomprises the carbon and the liquid layer comprises the precious metal.The remaining solid e-waste can be disposed of or further processed. Thefroth layer is generated by introducing a gas through the mixture.

The mixture comprising the e-waste, triiodide, at least one frothingagent and at least one collecting agent is preferably agitated, e.g.,stirred, as readily understood by the skilled artisan. Flotation can beperformed at room temperature in rectangular or cylindrical mechanicallyagitated cells or tanks, flotation columns, Jameson cells or deinkingflotation machines. It should be appreciated that the gas introduced toproduce the froth can comprise air, nitrogen, oxygen, argon, helium,carbon dioxide, dinitrogen monoxide, hydrogen, and any combinationthereof. Preferably the gas comprises air and the froth is produced bybubbling. It should be appreciated by the skilled artisan that thebubbling rate is easily determined to effectuate the formation of thefroth. Gas can be introduced to the cells, tanks, or columns usingfritted tubes. The froth layer can be easily separated from the liquidlayer by “skimming” or otherwise scraping the froth off of the liquidlayer, as readily understood by the skilled artisan. In addition, thefroth layer can be allowed to overflow the rim of the cell or containerwithout skimming or scraping. Following separation of the froth layerfrom the liquid layer, the froth layer can be processed to reclaim theconcentrated carbonaceous material contained therein, and the liquidlayer can be processed to reclaim the precious metal. The remainingsolid e-waste can be disposed of or further processed. Preferably, theliquid layer is aqueous.

Although not wishing to be bound by theory, the frothing agent isthought to reduce the surface tension of the water to stabilize therising air bubbles into a layer of foam on which hydrophilic materials,e.g., carbon, collect. The at least one frothing agent is preferablyenvironmentally friendly and comprises formally hydrated terpenesincluding, but not limited to, terpineols, citronellol, menthol,linalool, borneol, isoborneol, fenchyl alcohol, dihydromyrcenol, nerol,and combinations thereof, as illustrated below. Other frothing agentsinclude methyl isobutyl carbinol (MIBC). The frothing agent preferablyis substantially devoid of methyl isobutyl carbinol and other frothingagents derived from non-renewable resources. Preferably, the frothingagent comprises a terpineol.

Although not wishing to be bound by theory, the collecting agent isthought to preferentially adsorb to one of the components in themixture, e.g., carbon, rendering it more hydrophobic so that itassociates with the rising air bubbles. The at least one collectingagent is preferably environmentally friendly and comprises unsaturatedhydrocarbon terpenes including, but not limited to, limonene,phellandrenes, terpinenes, pinene, camphene, car-3-ene, sabinene,thujenes, allo-ocimene, ocimenes, myrcene, dihydromyrcene, andcombinations thereof, as illustrated below. The collecting agentpreferably is substantially devoid of kerosene and other collectingagents derived from non-renewable resources. Preferably, the collectingagent comprises limonene.

Preferably, the collecting agent comprises limonene and the frothingagent comprises a terpineol.

Accordingly, in yet another embodiment, an apparatus for recycling a PWBand/or PWB component is described, said apparatus comprising carbon andprecious metal removal means comprising:

a precious metal leaching module comprising a container for a leachingcomposition comprising tri-iodide, at least one frothing agent, and atleast one collecting agent;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB and/or PWBcomponent moves automatically or manually from the precious metalleaching module to the rinsing module and to the drying module. In aparticularly preferred embodiment, the PWB and/or PWB component moves ona conveyer belt, conveying rollers, or conveying wheels through theapparatus. Preferably, PWB components are pulverized.

In still another embodiment, an apparatus for recycling a PWB and/or PWBcomponent is described, said apparatus comprising carbon and preciousmetal removal means comprising:

a crushing module;a precious metal leaching module comprising a container for a leachingcomposition comprising tri-iodide, at least one frothing agent, and atleast one collecting agent;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the PWB and/or PWBcomponent moves automatically or manually from the precious metalleaching module to the rinsing module and to the drying module. In aparticularly preferred embodiment, the PWB and/or PWB component moves ona conveyer belt, conveying rollers, or conveying wheels through theapparatus. Preferably, PWB components are pulverized.

The apparatus comprising carbon and precious metal removal means canfurther comprise a heating module, as described herein, which can beeasily incorporated into the apparatus subsequent to the precious metalleaching module.

With regards to the leaching composition, the leaching composition forremoving carbon and precious metals from e-waste comprises, consists of,or consists essentially of at least one oxidizing agent, at least oneiodide salt or hydroiodic acid, at least one frothing agent, at leastone collecting agent, and water. In another embodiment, the leachingcomposition comprises, consists of, or consists essentially of at leastone oxidizing agent, at least one iodide salt or hydroiodic acid, water,at least one frothing agent, at least one collecting agent, and at leastone organic solvent. In still another embodiment, the leachingcomposition comprises, consists of, or consists essentially of at leastone oxidizing agent, at least one iodide salt or hydroiodic acid, water,at least one frothing agent, at least one collecting agent, and at leastone metal passivating agent. In still another embodiment, the leachingcomposition comprises, consists of, or consists essentially of at leastone oxidizing agent, at least one iodide salt or hydroiodic acid, water,at least one metal passivating agent, at least one frothing agent, atleast one collecting agent, and at least one buffering agent. In stillanother embodiment, the leaching composition comprises, consists of, orconsists essentially of at least one oxidizing agent, at least oneiodide salt or hydroiodic acid, water, at least one frothing agent, atleast one collecting agent, and at least one surfactant. In yet anotherembodiment, the leaching composition comprises, consists of, or consistsessentially of at least one oxidizing agent, at least one iodide salt orhydroiodic acid, water, at least one organic solvent, at least onefrothing agent, at least one collecting agent, and at least one metalpassivating agent. In yet another embodiment, the leaching compositioncomprises, consists of, or consists essentially of at least oneoxidizing agent, at least one iodide salt or hydroiodic acid, water, atleast one organic solvent, at least one frothing agent, at least onecollecting agent, and at least one surfactant. In yet anotherembodiment, the leaching composition comprises, consists of, or consistsessentially of at least one oxidizing agent, at least one iodide salt orhydroiodic acid, water, at least one surfactant, at least one frothingagent, at least one collecting agent, and at least one metal passivatingagent. In yet another embodiment, the leaching composition comprises,consists of, or consists essentially of at least one oxidizing agent, atleast one iodide salt or hydroiodic acid, water, at least one organicsolvent, at least one surfactant, at least one frothing agent, at leastone collecting agent, and at least one metal passivating agent. It isunderstood that the iodide salt or hydroiodic acid and the oxidizingagent present in the leaching composition will react to form iodine insitu and iodide ion will be in excess, resulting in the formation oftriiodide. Accordingly, the leaching composition subsequent to the insitu reaction will comprise, consist of, or consist essentially oftriiodide, at least one frothing agent, at least one collecting agent,and water. In another embodiment, the leaching composition subsequent tothe in situ reaction will comprise, consist of, or consist essentiallyof triiodide, water, at least one frothing agent, at least onecollecting agent, and at least one organic solvent. In still anotherembodiment, the leaching composition subsequent to the in situ reactionwill comprise, consist of, or consist essentially of triiodide, water,at least one frothing agent, at least one collecting agent, and at leastone passivating agent. In still another embodiment, the leachingcomposition subsequent to the in situ reaction will comprise, consistof, or consist essentially of triiodide, water, at least one frothingagent, at least one collecting agent, and at least one surfactant. Inyet another embodiment, the leaching composition subsequent to the insitu reaction will comprise, consist of, or consist essentially oftriiodide, water, at least one organic solvent, at least one frothingagent, at least one collecting agent, and at least one passivatingagent. In yet another embodiment, the leaching composition subsequent tothe in situ reaction will comprise, consist of, or consist essentiallyof triiodide, water, at least one organic solvent, at least one frothingagent, at least one collecting agent, and at least one surfactant. Inyet another embodiment, the leaching composition subsequent to the insitu reaction will comprise, consist of, or consist essentially oftriiodide, water, at least one surfactant, at least one frothing agent,at least one collecting agent, and at least one passivating agent. Inyet another embodiment, the leaching composition subsequent to the insitu reaction will comprise, consist of, or consist essentially oftriiodide, water, at least one organic solvent, at least one surfactant,at least one frothing agent, at least one collecting agent, and at leastone passivating agent.

Accordingly, in a sixth aspect, a method of removing carbon and at leastone precious metal from e-waste is described, said method comprising:

introducing the PWBs and/or PWB components to a leaching compositioncomprising triiodide, at least one frothing agent, and at least onecollecting agent;generating a froth layer and a liquid layer; andseparating the froth layer from a liquid layer,wherein the precious metals are substantially removed into the liquid,and the carbon is substantially removed into the froth.

Apparatus and Method for Recycling PWBs

In a seventh aspect, an apparatus for recycling e-waste, e.g., PWBs isdescribed, said apparatus comprising in general a desoldering apparatusand a precious metal leaching apparatus (see, FIG. 6). The desolderingapparatus can correspond to that of the first or third aspect describedherein, although it should be appreciated that other desolderingapparatuses can be used. The precious metal leaching apparatus cancorrespond to that of the fifth aspect described herein, although itshould be appreciated that other precious metal leaching apparatuses canbe used. Preferably, the apparatus is designed such that the e-waste,e.g., PWB, crushed IC powders, etc., moves automatically or manuallyfrom the desoldering apparatus to the precious metal leaching apparatus.In a particularly preferred embodiment, the e-waste, e.g., PWB, moves ona conveyer belt, conveying rollers, or conveying wheels through theapparatus. Preferably, the desoldering apparatus and the precious metalleaching apparatus are attached such that the e-waste movesautomatically and contiguously from one to the other.

In one embodiment of the seventh aspect, an apparatus for recyclinge-waste comprises:

a mechanical solder removal module;a chemical solder removal module;a rinsing module;a drying module;a precious metal leaching module;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the e-waste movesautomatically or manually module to module. In a particularly preferredembodiment, the e-waste moves on a conveyer belt, conveying rollers, orconveying wheels through the apparatus. Preferably, the modules areattached such that the e-waste moves automatically and contiguously fromone to the other. In a particularly preferred embodiment, the e-wastecomprises PWBs and the precious metals comprise gold.

In another embodiment of the seventh aspect, an apparatus for recyclinge-waste comprises:

a mechanical solder removal module, comprising at least one blade and atleast one agitator for the mechanical removal of solder from thesurface;a chemical solder removal module comprising a container for a firstcomposition and at least one agitator, wherein the PWB is partiallyimmersed in the first composition;a rinsing module;a drying module;a precious metal leaching module comprising a container for a leachingcomposition comprising tri-iodide;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the e-waste movesautomatically or manually module to module. In a particularly preferredembodiment, the e-waste moves on a conveyer belt, conveying rollers, orconveying wheels through the apparatus. Preferably, the modules areattached such that the e-waste moves automatically and contiguously fromone to the other. In a particularly preferred embodiment, the e-wastecomprises PWBs and the precious metals comprise gold. Preferably, theagitator comprises at least one brush, rake, or blown gases or liquids.

In yet another embodiment of the seventh aspect, an apparatus forrecycling e-waste comprises:

a mechanical solder removal module;a chemical solder removal module;a heating module;a rinsing module;a drying module;optionally, a crushing module;a precious metal leaching module;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the e-waste movesautomatically or manually module to module. In a particularly preferredembodiment, the e-waste moves on a conveyer belt, conveying rollers, orconveying wheels through the apparatus. Preferably, the modules areattached such that the e-waste moves automatically and contiguously fromone to the other. In a particularly preferred embodiment, the e-wastecomprises PWBs and the precious metals comprise gold. It is contemplatedthat subsequent to the heating module that the e-waste can bere-introduced to the chemical solder remover, the rinsing module, andthe drying module, as shown as an option in FIG. 3 and described herein.When present, the crushing module includes, but is not limited to, meansfor pulverizing, means for shredding, and means for crushing the PWBand/or PWB components so that the hard shell (e.g., plastic) is cracked,as readily determined by the person skilled in the art.

In still another embodiment of the seventh aspect, an apparatus forrecycling e-waste comprises:

a mechanical solder removal module, comprising at least one blade and atleast one agitator for the mechanical removal of solder from thesurface;a chemical solder removal module comprising a container for a firstcomposition and at least one agitator, wherein the PWB is partiallyimmersed in the first composition;a heating module;a rinsing module;a drying module;optionally, a crushing module;a precious metal leaching module comprising a container for a leachingcomposition comprising tri-iodide;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the e-waste movesautomatically or manually module to module. In a particularly preferredembodiment, the e-waste moves on a conveyer belt, conveying rollers, orconveying wheels through the apparatus. Preferably, the modules areattached such that the e-waste moves automatically and contiguously fromone to the other. In a particularly preferred embodiment, the e-wastecomprises PWBs and the precious metals comprise gold. It is contemplatedthat subsequent to the heating module that the e-waste can bere-introduced to the chemical solder remover, the rinsing module, andthe drying module, as shown as an option in FIG. 3 and described herein.When present, the crushing module includes, but is not limited to, meansfor pulverizing, means for shredding, and means for crushing the PWBand/or PWB components so that the hard shell (e.g., plastic) is cracked,as readily determined by the person skilled in the art. Preferably, theagitator comprises at least one brush, rake, or blown gases or liquids.

In another embodiment of the seventh aspect, an apparatus for recyclinge-waste comprises:

a mechanical solder removal module;a chemical solder removal module;optionally, a heating module;a rinsing module;a drying module;a crushing module;a precious metal leaching module;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the e-waste movesautomatically or manually module to module. In a particularly preferredembodiment, the e-waste moves on a conveyer belt, conveying rollers, orconveying wheels through the apparatus. Preferably, the modules areattached such that the e-waste moves automatically and contiguously fromone to the other. In a particularly preferred embodiment, the e-wastecomprises PWBs and the precious metals comprise gold. When present, itis contemplated that subsequent to the heating module that the e-wastecan be re-introduced to the chemical solder remover, the rinsing module,and the drying module, as shown as an option in FIG. 3 and describedherein. The crushing module includes, but is not limited to, means forpulverizing, means for shredding, and means for crushing the PWB and/orPWB components so that the hard shell (e.g., plastic) is cracked, asreadily determined by the person skilled in the art.

In still another embodiment of the seventh aspect, an apparatus forrecycling e-waste comprises:

a mechanical solder removal module, comprising at least one blade and atleast one agitator for the mechanical removal of solder from thesurface;a chemical solder removal module comprising a container for a firstcomposition and at least one agitator, wherein the PWB is partiallyimmersed in the first composition;optionally, a heating module;a rinsing module;a drying module;a crushing module;a precious metal leaching module comprising a container for a leachingcomposition comprising tri-iodide;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the e-waste movesautomatically or manually module to module. In a particularly preferredembodiment, the e-waste moves on a conveyer belt, conveying rollers, orconveying wheels through the apparatus. Preferably, the modules areattached such that the e-waste moves automatically and contiguously fromone to the other. In a particularly preferred embodiment, the e-wastecomprises PWBs and the precious metals comprise gold. When present, itis contemplated that subsequent to the heating module that the e-wastecan be re-introduced to the chemical solder remover, the rinsing module,and the drying module, as shown as an option in FIG. 3 and describedherein. The crushing module includes, but is not limited to, means forpulverizing, means for shredding, and means for crushing the PWB and/orPWB components so that the hard shell (e.g., plastic) is cracked, asreadily determined by the person skilled in the art. Preferably, theagitator comprises at least one brush, rake, or blown gases or liquids.

In still another embodiment of the seventh aspect, an apparatus forrecycling e-waste comprises:

a heating module, comprising a heating mechanism and means for movingthe waste PWBs through the heating mechanism;a chemical solder removal module comprising a container for a firstcomposition and at least one agitator, wherein the PWB is partiallyimmersed in the first composition;a rinsing module;a drying module;a precious metal leaching module comprising a container for a leachingcomposition comprising tri-iodide;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the e-waste movesautomatically or manually module to module. In a particularly preferredembodiment, the e-waste moves on a conveyer belt, conveying rollers, orconveying wheels through the apparatus. Preferably, the modules areattached such that the e-waste moves automatically and contiguously fromone to the other. In a particularly preferred embodiment, the e-wastecomprises PWBs and the precious metals comprise gold. Preferably, theheating module comprises agitation means comprising brushes and themeans for moving the waste PWBs through the heating mechanism comprisesa roller chain. The waste PWB can be hung from the roller chain usingclips or other clamping means. In a particular preferred embodiment, theheating mechanism is maintained at least 1° C. to about 20° C. below themelting point of the solder or epoxy.

In yet another embodiment of the seventh aspect, an apparatus forrecycling e-waste comprises:

a heating module, comprising a heating mechanism and means for movingthe waste PWBs through the heating mechanism;a chemical solder removal module comprising a container for a firstcomposition and at least one agitator, wherein the PWB is partiallyimmersed in the first composition;a rinsing module;a drying module;a crushing module;a precious metal leaching module comprising a container for a leachingcomposition comprising tri-iodide;a rinsing module; anda drying module.Preferably, the apparatus is designed such that the e-waste movesautomatically or manually module to module. In a particularly preferredembodiment, the e-waste moves on a conveyer belt, conveying rollers, orconveying wheels through the apparatus. Preferably, the modules areattached such that the e-waste moves automatically and contiguously fromone to the other. In a particularly preferred embodiment, the e-wastecomprises PWBs and the precious metals comprise gold. The crushingmodule includes, but is not limited to, means for pulverizing, means forshredding, and means for crushing the PWB and/or PWB components so thatthe hard shell (e.g., plastic) is cracked, as readily determined by theperson skilled in the art. Preferably, the heating module comprisesagitation means comprising brushes and the means for moving the wastePWBs through the heating mechanism comprises a roller chain. The wastePWB can be hung from the roller chain using clips or other clampingmeans. In a particular preferred embodiment, the heating mechanism ismaintained at least 1° C. to about 20° C. below the melting point of thesolder or epoxy.

Regardless of which embodiment of the seventh aspect is used, consistentwith the disclosures herein, the solder can comprise lead, tin, or acombination of lead and tin. Preferably, the e-waste comprises a surfacewhich includes a PWB and the recyclable material comprises components(e.g., ICs), precious metals, base metals, or any combination ofcomponents, precious metals and base metals. The released components canbe collected and can be separated into those that are reusable and canbe resold and those that can be further processed for disposal,reclamation of useful materials, etc. The first composition preferablyselectively removes solder (e.g., lead, tin, alloys thereof, andcombinations thereof) relative to precious metals, and/or base metals,and the components that are liberated following removal of the solderare readily collected and sorted for reuse or reclamation purposes.Subsequent to solder removal, the first composition, which includes leadand/or tin ions, can be subjected to further processing (e.g.,electrowinning) to reclaim the lead and/or tin. Preferably, prior tointroducing to the precious metal leaching module, the e-waste iscrushed. Subsequent to leaching, the gold can be precipitated asdescribed herein. The conditions of contact (i.e., time and temperature)were introduced herein. Advantageously, the apparatus allows a user totake obsolete and used printed wire boards and recycle the electroniccomponents and metals contained thereon for reuse.

In an eighth aspect, a method of recycling e-waste is described, saidmethod comprising:

removing at least a portion of the solder using a mechanical solderremover;removing at least a portion of the solder using a chemical solderremover; andremoving at least a portion of a precious metal using a leachingcomposition.The process can further comprise rinsing and drying of the e-waste.Preferably, the e-waste comprises a PWB.

In one embodiment of the eighth aspect, a method of recycling e-waste isdescribed, said method comprising:

removing at least a portion of the solder using a mechanical solderremover, wherein the mechanical solder remover comprises at least oneblade and at least one agitator for the mechanical removal of solderfrom the surface;removing at least a portion of the solder using a chemical solderremover, wherein the chemical solder remover comprises a container for afirst composition and at least one agitator, wherein the PWB ispartially immersed in the first composition; andremoving at least a portion of a precious metal using a leachingcomposition.The process can further comprise rinsing and drying of the e-waste.Preferably, the e-waste comprises a PWB. Preferably, the agitatorcomprises at least one brush, rake, or blown gases or liquids.

In yet another embodiment of the eighth aspect, a method for recyclinge-waste comprises: removing at least a portion of the solder using amechanical solder remover;

removing at least a portion of the solder using a chemical solderremover;removing epoxy-covered components using heating means; andremoving at least a portion of a precious metal using a leachingcomposition.The process can further comprise rinsing and drying of the e-waste.Preferably, the e-waste comprises a PWB. Preferably, the mechanicalsolder remover comprises at least one blade and at least one agitatorfor the mechanical removal of solder from the surface of the e-waste.Preferably, the chemical solder remover comprises a container for afirst composition and at least one agitator, wherein the e-waste ispartially immersed in the first composition. Preferably, the agitatorcomprises at least one brush, rake, or blown gases or liquids.

Although the invention has been variously disclosed herein withreference to illustrative embodiments and features, it will beappreciated that the embodiments and features described hereinabove arenot intended to limit the invention, and that other variations,modifications and other embodiments will suggest themselves to those ofordinary skill in the art, based on the disclosure herein. The inventiontherefore is to be broadly construed, as encompassing all suchvariations, modifications and alternative embodiments within the spiritand scope of the claims hereafter set forth.

1.-33. (canceled)
 34. An apparatus for removing solder from a surface ofa printed wire board (PWB) having at least one casing and/or componentaffixed thereto by solder or epoxy, the apparatus comprising: a heatingmodule; and chemical solder removal means.
 35. The apparatus of claim34, wherein the apparatus comprises: a heating module; a chemical solderremoval module; a rinsing module; and a drying module.
 36. The apparatusof claim 34, wherein the heating module comprises means for moving thePWB through a heating mechanism.
 37. The apparatus of claim 36, whereinthe heating mechanism comprises agitation means for removing the solderand/or the casing and/or the epoxied component.
 38. The apparatus ofclaim 36, wherein the means for moving the PWB in the heating modulecomprise a roller chain, track, belt, and/or link chain.
 39. Theapparatus of claim 36, wherein the heating module comprises anattachment region for attaching the PWB to the means for moving.
 40. Theapparatus of claim 36, wherein the heating module comprises adisattachment region for disattaching the PWB from the means for moving.41. The apparatus of claim 36, wherein the means for moving furthercomprises holding means.
 42. The apparatus of claim 41, wherein theholding means comprise clips or clamps.
 43. The apparatus of claim 41,wherein the PWB is attached to the holding means manually orautomatically.
 44. The apparatus of claim 40, wherein the disattachmentregion comprises a trough to collect the disattached PWB.
 45. Theapparatus of claim 34, wherein the heating module further comprises aparts drawer
 46. The apparatus of claim 36, wherein the heatingmechanism comprises resistance heating coils.
 47. The apparatus of claim36, wherein the heating mechanism further comprises at least one of avent, an air scrubber and a filter.
 48. The apparatus of claim 37,wherein the agitation means comprises at least one brush, rake, sonicenergy, laser energy, pressurized gas, and pressurized liquid.
 49. Theapparatus of claim 34, wherein the solder comprises lead, tin, alloysthereof, and combinations thereof.
 50. The apparatus of claim 34,further comprising means to move the PWB manually or automaticallythrough the apparatus.
 51. The apparatus of claim 34, wherein thechemical solder removal means comprise a vessel.
 52. The apparatus ofclaim 51, wherein the vessel comprises a drum.
 53. The apparatus ofclaim 34, wherein the chemical solder removal means comprises acontainer for a first composition.